Release notes/1.16

= MediaWiki 1.16 =

MediaWiki 1.16.x
Version bumps not documented here can be dated by the edit history at Template:MW stable release number.

MediaWiki 1.16.0
2010-07-28

This is a stable release of the MediaWiki 1.16 branch.

Summary of selected changes in 1.16
Selected changes since MediaWiki 1.15 that may be of interest:


 * Watchlists now have RSS/Atom feeds. RSS feeds generally are now hidden, since Atom is a better protocol and is supported by virtually all clients.
 * It's now possible to block users from sending email via Special:Emailuser.
 * The maintenance script system was overhauled. Most maintenance scripts now have a useful help page when you run them with --help.
 * AdminSettings.php is no longer required in order to run maintenance scripts. You can just set and  in your LocalSettings.php instead.
 * The preferences system was overhauled. Preferences are stored in a more compact format. Changes to site default preferences will automatically affect all users who have not chosen a different preference.
 * Support for SQLite was improved. Some broken features were fixed, and it now has an efficient full-text search.
 * The user groups ACL system was improved by allowing rights to be revoked, instead of just granted.
 * A new localisation caching system was introduced, which will make MediaWiki faster for almost everyone, especially when lots of extensions are enabled.

By default, this new system makes a lot of database queries. If your database is particularly slow, or if your system administrator limits your query count, or if you want to squeeze as much performance as possible out of Mediawiki, set to a writable path on the local filesystem. Make sure you have the DBA extension for PHP installed, this will improve performance further.

Changes since 1.16 beta 3

 * (bug 23769) Disabled HTML 5 client-side form validation. Was introduced in 1.16 beta 1, but is currently poorly supported by browsers.
 * (bug 23175) Re-added window.ta variable for backwards compatibility.
 * (bug 23264) Fixed breakage of various command line scripts due to extra line endings being inserted by Maintenance::output.
 * Fixed HTTP client functionality with safe_mode=On.
 * Fixed parser tests broken in 1.16 beta 3.
 * For Oracle DB backend: fixed parser tests and table prefix feature.
 * (bug 23767) Fixed PHP warning when REQUEST_URI is blank (IIS issue).
 * Fixed plural function for Northern Sami (se)
 * (bug 23597) Fixed conflicts between ID attributes in the Vector skin and parser-generated heading IDs. Renamed head, panel, head-base and page-base.
 * Disabled >1 feature on SQLite, does not work yet.
 * (bug 23465) Don't ignore the predefined destination filename on Special:Upload after following a red link to a file.
 * In SQLite full-text search feature: fixed "move page" feature, was non- functional.
 * (bug 24565) Fixed Cache-Control headers sent from API modules, to protect user privacy in the case where an attacker can access the wiki through the same HTTP proxy as a logged-in user.
 * Fixed an XSS vulnerability in profileinfo.php for installations with = true (false by default)
 * Fixed a case where an X-Vary-Options header was sent despite being false. Fixed a minor header parsing issue when  = true.
 * Fixed a register_globals arbitrary inclusion vulnerability in MediaWikiParserTest.php, introduced in 1.16 beta 1.

Changes since 1.16 beta 2

 * Fixed bugs in the Special:Userlogin and Special:Emailuser handling of invalid usernames.
 * Fixed sorting in Special:Allmessages
 * (bug 23113) Fixed title in the show/hide links on diff pages
 * (bug 23117) Fixed API rollback, was returning "badtoken" for valid requests
 * (bug 23127) Re-added missing $1 parameter to the uploadtext message
 * Fixed a bug in the Vector skin where personal tools display behind the logo
 * (bug 23139) Fixed a bug in edit conflict resolution, where both textboxes showed the same text.
 * (bug 23115, bug 23124) Fixed various problems with and elements in page views and previews when the language converter is enabled.
 * (bug 23148) Fixed a local path disclosure vulnerability in ImageMagick image scaling, which was introduced in 1.16 beta 1.
 * Improved error checking on installer.
 * (bug 22970) Fixed a JavaScript error in the upload destination conflict check.
 * (bug 23167) Check the watch checkbox by default if the watchcreations preference is set.
 * (bug 23171) Improve IE6 version check to avoid false positives.
 * (bug 23176) Fixed upload warning override feature "upload new version", broken in 1.16 beta 1.
 * Fixed regression in unwatch links sent out in notification emails. When the mailing job was deferred via the job queue, the title was incorrect.
 * (bug 23534) Fixed SQL query error in API list=allusers.
 * Fixed a bug in uploads for non-JavaScript clients. An empty string was used as the default destination filename, instead of the source filename as expected.
 * (bug 23371) Fixed CSRF vulnerability in "e-mail me my password", "create account" and "create by e-mail" features of Special:Userlogin
 * (bug 23687) Fixed XSS vulnerability affecting IE clients only, due to a CSS validation issue.
 * Fixed a DoS vulnerability in ImageMagick image scaling. ImageMagick expanded wildcard characters "?" and "*" in image filenames, potentially causing large numbers of images to be scaled in response to a single request. The fix for this involves breaking the scaling of such image filenames until ImageMagick 6.6.1-5 or later is deployed, see bug 23361 for more details.
 * (bug 23608) Fixed invalid HTML in diff pages.

Configuration changes in 1.16

 * is deprecated in favor of
 * (bug 18222) default is now 1
 * can be used to configure session.save_handler
 * / now have a 'fileMode' parameter to be used when uploading/moving files
 * (bug 18761) is a new array for specifying preferences not to be shown to users
 * and were deprecated in favor of [] = 'realname', but the former are still retained for backwards-compatibility
 * (bug 9257) now defaults to three months
 * can be set to true to show warnings about deprecated functions and other potential errors when developing.
 * Subpages are now enabled in the MediaWiki namespace by default. This is mainly a cosmetic change, and does not in any way affect the MessageCache, which was already effectively treating the namespace as if it had subpages.
 * Oracle: maintenance/ora/user.sql script for creating DB user on oracle with appropriate privileges. Creating this user with web-install page requires oci8.privileged_connect set to On in php.ini.
 * Removed UserrightsChangeableGroups hook introduced in 1.14
 * Added, to replace , , and any other local caches which need a place to put files.
 * is no longer set to anything by default, and so either needs to be set explicitly, or needs to be set instead.
 * has been removed. Instead, set to true
 * Removed and . Similar functionality is now available via.
 * ->addMessages is deprecated. Messages added via this interface will not appear in Special:AllMessages.
 * can be used to record external links pointing to same server
 * (bug 19907) and  added to control which external domains may access the API via cross-site AJAX.
 * for extensions to add their scripts to the default list
 * has been added, default value '50M'
 * is deprecated, the SpecialRandomGetRandomTitle hook should be used instead
 * (bug 20489) added to override the default list of illegal characters in file names.
 * (bug 19646) added to display reason access to uploaded file was denied to users(img_auth only)
 * (bug 19646) added to test to see if img_auth set up correctly (img_auth only)
 * added to disable file deletions and restorations during maintenance
 * added to configure per-namespace capitalization
 * (bug 21172) can now be an array with multiple DNSBL and renamed to  (backward compatibility kept)
 * has been removed
 * (bug 3340) added (default: 16) to configure the low end of CIDR ranges for blocking
 * added for quick and easy enabling of Commons as a remote file repository
 * added to choose a DBA handler when using CACHE_DBA
 * for extensions that create namespaces that behave similarly to the category namespace.
 * renamed to ( kept for backward compatibility)
 * now also affects images inline images that do not exist. In that case the URL will get (?|&)wpDestFile=&lt;filename> appended to it as appropriate.
 * If is null, use the server's timezone as the default for signatures. This was always the behaviour documented in DefaultSettings.php but has not been the actual behaviour for some time: instead, UTC was used by default.
 * Added, to decouple assets serving from . If not specified it will default to /extensions
 * Added to make search UI display total number of hits with some search engines.
 * Added to decide what feed types (RSS, Atom, both, or neither) MediaWiki advertises. Default is array( 'atom' ), so RSS is no longer advertised by default (but it still works).
 * Added, controls how long to wait for data from the memcached servers.
 * New configuration variables and  for controlling debug output.
 * New when set to true disallows blocked users from logging in.
 * (bug 8790) Metadata edition has been moved to a separate extension "MetadataEdit".

New features in 1.16

 * Add CSS defintion of the 'wikitable' class to shared.css
 * (bug 17163) Added MediaWiki:Talkpageheader which will be displayed when viewing talk pages
 * Superfluous border="0" removed from images
 * Added new hook 'MessageCacheReplace' into MessageCache.php. For instance to allow extensions to update caches in similar way as MediaWiki invalidates a cached MonoBook sidebar
 * Special:AllPages: Move hardcoded styles from code to CSS
 * (bug 18529) New hook: SoftwareInfo for adding information about the software to Special:Version
 * Added to allow extensions to easily alter the data type of columns when using the Postgres backend.
 * (bug 16950) Show move log when viewing/creating a deleted page
 * (bug 18242) Show the Subversion revision number per extensions in Special:Version
 * (bug 18420) Missing file revisions are handled gracefully now
 * (bug 9219) Auth plugins can control editing RealName/Email/Nick preferences
 * (bug 18466) Add note or warning when overruling a move (semi-)protection
 * (bug 18342) insertTags works in edit summary box
 * (bug 18411) The upload form also checks post_max_size
 * Watchlist now has a specialized  tag that contains a unique class for each page
 * Added Minguo calendar support for the Taiwan Chinese language
 * Database: unionQueries function to be used for UNION sql construction, so it can be overloaded on DB abstraction level for DB specific functionality
 * (bug 18849) Implement Japanese and North Korean calendars
 * (bug 5755) Introduce and  to display the month number without the leading zero
 * (bug 13456) categoriespagetext supports PLURAL
 * (bug 18860) Blocks of IPs affecting registered users can now block email
 * (bug 17093) Date and time are separate parameters in Special:BlockList
 * (bug 11484) Added ISO speed rating to default collapsed EXIF metadata view
 * (bug 14866) Messages 'recentchangeslinked-toolbox' and 'recentchangeslinked-toolbox' were added to allow more fine grained customisation of the user interface
 * DISPLAYTITLE now accepts a limited amount of wiki markup (the single-quote items)
 * Special:Search now could search terms in all variant-forms. ONLY apply on wikis enabled LanguageConverter.
 * Add autopromote condition APCOND_BLOCKED to autopromote blocked users to various user groups.
 * Add as a means of restricting a group's rights. The syntax is identical to, but users in these groups will have these rights stripped from them.
 * Added a PHP port of CDB (constant database), for improved local caching when the DBA extension is not available.
 * Introduced a new system for localisation caching. The system is based around fast fetches of individual messages, minimising memory overhead and startup time in the typical case. The database backend will be used by default, but set to get a faster CDB-based implementation.
 * Expanded the number of variables which can be set in the extension messages files.
 * Added a feature to allow per-article process pool size control for the parsing task, to limit resource usage when the cache for a heavily-viewed article is invalidated. Requires an external daemon.
 * (bug 19576) Moved the id attribues from the anchors accompanying section headers to the elements within the section headers, removing the redundant anchor elements.
 * Parser::setFunctionTagHook now can be used to add a new tag which is parsed at preprocesor level.
 * Added, allowing sysadmins to disable thumbnail display for old versions of images.
 * In watchlists and Special:RecentChanges, the difference in page size now appears in dark green if bytes were added and dark red if bytes were removed.
 * Added FSRepo configuration properties thumbUrl and thumbDir, to allow the thumbnails to be stored in a separate location to the source images.
 * If config/ directory is not executable, the command to make it executable now asks the user to cd to the correct directory
 * Add experimental new external authentication framework, ExternalAuth
 * (bug 18768) Remove AdminSettings requirements. Maintenance environment will still load it if it exists, but it's not required for anything
 * (bug 19900) The "listgrouprights-key" message is now wrapped in a div with class "mw-listgrouprights-key"
 * (bug 471) Allow RSS feeds for watchlist, using an opt-in security token
 * (bug 10812) Interwiki links can have names and descriptions, fetched from message 'interwiki-desc-PREFIX', not really used anywhere yet though
 * (bug 9691) Add type (signup or login) parameter to AuthPlugin::ModifyUITemplate
 * (bug 14454) "Member of group(s)" in Special:Preferences causes language difficulties
 * (bug 16697) Unicode combining characters are difficult to edit in some browsers
 * Parser test supports uploading results to remote CodeReview instance
 * (bug 20013) Added CSS class "mw-version-ext-version" is wrapped on the extension version in Special:Version
 * (bug 20014) Added CSS class "mw-listgrouprights-right-name" is wrapped on the right name in Special:ListGroupRights
 * (bug 12920) New CoreParserFunction as an url-friendly equivalent to
 * (bug 16322) Allow maintenance scripts to accept DB user/pass over input or params
 * (bug 18566) Maintenance script to un/protect pages
 * (bug 671) The HTML tag is now permitted.
 * RecentChanges now has a legend to explain what the Nmb! flags mean, and the flags have tooltips.
 * (bug 15209) New hook BeforeInitialize called after everything has been setup but before Mediawiki::performRequestForTitle
 * wgMainPageTitle variable now available to JavaScript code to identify the main page link, so it doesn't have to be extracted from the link URLs.
 * (bug 16836) Display preview of signature in user preferences and describe its use
 * The default output format is now HTML 5 instead of XHTML 1.0 Transitional. This can be disabled by setting = false;. Specific features enabled if HTML 5 is used:
 * Some extra inputs will be autofocused, in supporting browsers.
 * The summary attribute has been removed from tables of contents. summary is obsolete in HTML 5 and wasn't useful here anyway.
 * Unnecessary type="" attribute removed for CSS and JS.
 * If is set to false, some bytes will be shaved off of HTML output by omitting some things like quotation marks where HTML 5 allows.
 * (bug 16921) maxlength enabled for page move comments
 * The description message in can be an array with parameters
 * New hook SpecialRandomGetRandomTitle allows extensions to modify the selection criteria used by Special:Random and subclasses, or substitute a custom result, deprecating the config variable
 * (bug 20318) Distinct CSS classes for ISBN/RFC/PMID special links added
 * (bug 20404) Custom fields in the user creation form template can now have detail labels in prefsectiontip divs.
 * MakeSysop and MakeBot are now aliases for Special:UserRights
 * IndexPager->mLimitsShown can now be an associative array of limit => text-to- display-in-limit-form.
 * (bug 18880) LogEventsList::showLogExtract can now take a string-by-reference and add its HTML to it, rather than having to go straight to.
 * Added, to allow users to easily gather backtraces for database connection and query errors.
 * Show change block / unblock link on Special:Contributions if user is blocked
 * Display note on Special:Contributions if the user is blocked, and provide an excerpt from the block log.
 * (bug 19646) New hook: ImgAuthBeforeStream for tests and functionality before file is streamed to user, but only when using img_auth
 * Note on non-existing user and user talk pages if user does not exist * New hook ShowMissingArticle so extensions can modify the output for non-existent pages.
 * Admins could disable some variants using now. ONLY apply on wikis enabled LanguageConverter.
 * (bug 16310) Credits page now lists IP addresses rather than saying the number of anonymous users that edited the page
 * New permission 'sendemail' added. Default right for all registered users. Can for example be used to prevent new accounts from sending spam.
 * (bug 16979) Tracking categories for __INDEX__ and __NOINDEX__
 * Two new hooks, ConfirmEmailComplete and InvalidateEmailComplete, which are called after a user's email has been successfully confirmed or invalidated.
 * (bug 19741) Moved the XCF files out of the main MediaWiki distribution, for a smaller subversion checkout.
 * (bug 13750) First letter capitalization can now be a per-namespace setting
 * (bug 21073) "User does not exist" message no longer displayed on sub-sub-pages of existing users
 * (bug 21095) Tracking categories produced by the parser (expensive parser function limit exceeded, __NOINDEX__ tracking, etc) can now be disabled by setting the system message (MediaWiki:expensive-parserfunction-category etc) to "-".
 * Added maintenance script sqlite.php for SQLite-specific maintenance tasks.
 * Rewrote Special:Upload to allow easier extension.
 * Upload errors that can be solved by changing the filename now do not require reuploading.
 * Added, to allow specific IPs to be whitelisted from rate limits.
 * (bug 21222) When is not enabled,  is no longer registered with the parser so extensions are free to implement their own  tag
 * (bug 21047) Wrap 'cannotdelete' into a div with the generic 'error' class and an own 'mw-error-cannotdelete' class
 * New hook AbortNewAccountAuto, called before account creation from AuthPlugin- or ExtUser-driven requests.
 * (bug 3480) The warning saying that the page has a history when deleting it now contains the number of revisions in the history
 * and are now set in the default LocalSettings.php file.
 * (bug 20186) Allow filtering history for revision deletion.
 * New hook OtherBlockLogLink, called in Special:IPBlockList and Special:Block to show links to block logs of other blocking extensions, i.e. GlobalBlocking
 * Added search capabilities to SQLite backend
 * rebuildtextindex.php maintenance script now supports databases other than MySQL
 * upgrade1_5.php now requires to be run --update option to prevent confusion
 * (bug 17662) Customizable default preload/editintro for new sections in the respective addsection-preload and addsection-editintro messages
 * Added maintenance script checkSyntax.php that checks for PHP syntax errors and common coding mistakes
 * Updated Unicode normalization tables
 * (bug 21604) Spellcheck attribute for editsummary
 * New wgCategories JavaScript global variable for userscripts.
 * (bug 20717) Added checkboxes to hide users with bot and/or sysop group membership in SpecialActiveusers
 * Allow \pagecolor and \definecolor in texvc
 * contains background color for texvc call
 * (bug 21574) Redirects can now have "303 See Other" HTTP status
 * EditPage refactored to allow extensions to derive new edit modes much easier.
 * (bug 21826) Subsections of Special:Version now also have anchors
 * (bug 19791) Add URL of file source as comment to thumbs (for ImageMagick)
 * (bug 21946) Sorted wikitables do not properly handle minus signs
 * (bug 18885) Red links for media files do not support shared repositories
 * Added, to convert deprecated presentation forms in Arabic text to their modern equivalents, and , to convert ZWJ-based chillu sequences in Malayalam text to their Unicode 5.1 equivalents.
 * (bug 22051) Returing false in SpecialContributionsBeforeMainOutput hook now stops normal output
 * Send new password e-mail in users preference language
 * LanguageConverter now support nested using of manual convert syntax like "-{-{}-}-"
 * Upload license preview now uses the API instead of action=ajax
 * (bug 7346) Add to RSS to avoid duplicates
 * (bug 19996) Added new hooks for Special:Search, which allow to further restrict/expand it.
 * (bug 21936) When a revision has been patrolled, there's now a link back to the article
 * (bug 22315) SpecialRecentChangesQuery hook now pass $query_options and checks the return value
 * Separate unit test suites under t/ and tests/ were merged and moved to maintenance/tests/.
 * importImages.php maintenance script can now use the original uploader and comment from another wiki.
 * Support for Turck MMCache was removed
 * (bug 14592) Warn users when they try to move their user page that their account will not be renamed
 * Show block log on non-existing user (talk) pages of currently blocked users

Bug fixes in 1.16

 * (bug 18031) Make namespace selector on Special:Export remember the previous selection
 * The svn-version version numbers on Special:Version have been removed
 * (bug 17374) Special:Export no longer exports two copies of the same page
 * (bug 18190) Proper parsing in MediaWiki:Sharedupload message
 * (bug 17617) HTML cleanup for ImagePage
 * (bug 17964) namespaceDupes.php no longer fails on an empty interwiki table
 * Improved error handling for image moving
 * (bug 17974) On Special:SpecialPages, restricted special pages are now marked with tags, helps with text-based browsers
 * (bug 18259) Special:DeletedContributions now also uses MediaWiki:Sp-contributions-logs for the link to Special:Log
 * Don't add empty title="" attributes to links to anchors on the current page
 * (bug 18291) rebuildrecentchanges.php failed to add deletion log entries
 * (bug 18304) rebuildrecentchanges.php got size changes wrong
 * (bug 18170) Fixed a PHP warning in Parser::preSaveTransform in PHP 5.3
 * (bug 18289) Database connection error page now returns correct HTML
 * "successbox", "errorbox" and related CSS classes are now available in all skins
 * (bug 18316) Removed superfluous name="fulltext" from Special:Search
 * (bug 18331) MediaWiki:Undelete-revision can now have wikitext
 * The "noautoblock" flag is no longer displayed in the block log when blocking an IP address
 * (bug 18009) and  now support closures
 * (bug 17948) Maintenance scripts now exit(0) or exit(1) as appropriate
 * (bug 18377) Time in Enhanced ChangesList lacking localisation
 * (bug 12998) Allow ,   , etc. in DISPLAYTITLE
 * (bug 1553) Lowercase navigation headings in German
 * (bug 7830) Pending transactions failed to commit on loginToUse error
 * (bug 11613) session.save_handler being over-ridden
 * (bug 11381) session.save_handler being set twice (causes error)
 * (bug 17835) ForeignAPIRepo throwing error on first page load for file
 * (bug 18115) ForeignAPIRepo cache isn't working
 * Fixed a bug caused by LanguageConverter.php, which brings an abnormal '}-' after some parsed math syntax.
 * (bug 18441) rebuildrecentchanges.inc no longer ignores
 * (bug 18317) Bolded selections in 1 | 3 | etc days on RecentChanges now use instead of hardcoded styles
 * (bug 18449) Fixed items number per column on category pages when the total is divisible by 3
 * (bug 18121) maintenance/deleteArchivedRevisions.php no longer deletes revisions when --delete is not passed
 * (bug 13172) GPS coordinates in image Exif data are now actually displayed
 * Overhaul of preferences system, includes the following bug fixes:
 * (bug 5363) Changes to default preferences now impact registered users.
 * (bug 14806) Hook to enable putting preferences in existing tabs.
 * (bug 17191) Registration date now listed on preferences page.
 * The user_properties table (now used for storing preferences) has been added to.
 * Note that this change will break some extensions which have not been adapted for it.
 * (bug 17020) Adding fallback encodings for Traditional and Simplified Chinese languages while the the text is typed as URLs.
 * (bug 17614) Prev / Next links are not shown if all results are shown
 * (bug 18207) Strange spacing before irc:... links
 * Removed float from the user login form in RTL interface - caused display problems in FF2
 * (bug 15008) Redirect images are now subject to Bad image list rules
 * (bug 6802) profileinfo.php now also work on other database servers than MySQL
 * (bug 16925) Diffs no longer fail when is set to 'wikidiff' or 'wikidiff2' but extension is not installed
 * (bug 18326) Chmod errors in file repos have been hidden
 * (bug 18718) Comma after a } create a error in IE
 * (bug 18716) Removed redundant class in Modern skin CSS for category links and tweaked spacing.
 * (bug 18656) Use proper directory separators in wfMkdirParents
 * (bug 18549) Make Special:Blockip respect and
 * (bug 16912) Tooltips on images with link= disappear
 * (bug 18389) Localise numbers in EXIF data
 * (bug 18522) Wrap MediaWiki:Protect-cascadeon in a div for identification
 * (bug 18438) Tweak HTML for preview bar for consistency and accessibility
 * (bug 18432) Updated documentation for dumpBackup.php
 * Fix array logic in Sanitizer::removeHTMLtags so that it doesn't strip good tags that were redundantly defined.
 * (bug 14118) SpecialPage::getTitleFor does not return a localised name
 * (bug 18698) Renaming non entry point maintenance scripts from .inc.php to .inc
 * Deprecated methods Title::getInterwikiLink, Title::userCanCreate, Title::userCanEdit and Title::userCanMove have been removed
 * Only show upload links on file description if = true and user can upload
 * Don't say "You need to log in to upload/move", because it's possible that uploading/moving is disabled for registered users as well (e.g. only sysops)
 * (bug 18943) Handle invalid titles gracefully at Special:Mostlinked
 * (bug 8873) Enable variant conversion in text on 'alt' and 'title' attributes
 * (bug 10837) Introducing the StubUserVariant class to determine the variant variable instead of using this to overrules the user language preference.
 * (bug 19014) If user had deletedhistory right, but not undeleted right, then show "view" instead of "view/restore" on logs.
 * (bug 19017) TOC level calculation error in an odd case
 * (bug 18999) CSS update for RTL interwiki links
 * (bug 18925) history.js removes class names of list elements on initialization
 * Multiple whitespace in TOC anchors is now stripped, for consistency with the link from the edit comment
 * (bug 19112) Preferences now respects
 * (bug 18173) MediaWiki now fails when unable to determine a client IP
 * (bug 19170) Special:Version should follow the content language direction
 * (bug 19160) maintenance/purgeOldText.inc is now compatible with PostgreSQL
 * Fixed performance regression in "bad image list" feature
 * Show user preference 'Use live preview' if is enabled only
 * (bug 17014) Blocked users can no longer use Special:UserRights unless they can add/remove *all* groups (have 'userrights' permission).
 * (bug 19294) Always show Sp-contributions-footer(-anon)
 * Attempts to restrict reading of pages while anonymous viewing is allowed via extensions not using the userCan hook and via now work.
 * (bug 8445) Multiple-character search terms are now handled properly for Chinese
 * (bug 19450) Use formatNum for "Number of edits" in Special:Preferences
 * (bug 11242) Check for MySQL storage engines during installation now checks whether the engines are actually available
 * (bug 19390) Omit the "printable version" link on the printable version
 * (bug 18394) img_auth.php now respects userCan
 * (bug 19509) Uploading to a file named '0' previously treated it as null input and attempted to upload with the source name. Now warns about not having an extension (since 0.ext is perfectly valid)
 * (bug 19468) Enotif preferences are now only displayed when they are turned on
 * (bug 19442) Show/hide options on watchlist only work once
 * (bug 19602) PubMed Magic links now use updated NIH url
 * (bug 19637) externallinks have links to self
 * Don't load Opera 9.5 RTL fixes for Opera 9.6
 * Remove five-year-old KHTMLFixes.css, which is unlikely to be relevant anymore and was causing problems.
 * Removed repetition of URIs in the title attributes of external links.
 * (bug 19693) User name is now escaped in "Contributions for ..." link on Special:BlockIP
 * (bug 19571) Override buildConcat for SQLite.
 * Log in and log out links no longer return to page view when clicked from history view, edit page, or something similar
 * (bug 19513) RTL fixes for new Search UI
 * (bug 16497) Special:Allmessages is paginated
 * (bug 18708) CSS plainlinks class now available to all skins
 * (bug 19590) Database error messages no longer have "MySQL" hardcoded as the database type
 * (bug 19759) successbox on Special:Preferences now correctly aligned on standard, nostalgia and cologneblue skin
 * (bug 19814) interwiki links from file links ( Foo.jpg ) are no longer recorded in the pagelinks table
 * (bug 19784) date option "ISO 8601" produced illegal id
 * (bug 19761) Removed autogenerated &lt;meta keywords> tag with link data. Keyword set was not useful, and is ignored by modern search engines anway.
 * (bug 19827) Special:SpecialPages title is "Upload file
 * (bug 19355) Added .xhtml, .xht to upload file extension blacklist
 * (bug 19287) Workaround for lag on history page in Firefox 3.5
 * (bug 19564) Updated docs/hooks.txt
 * (bug 18751) Fix for buggage in profiling setup for some extensions on PHP 5.1
 * (bug 17139) ts_resortTable inconsistent trimming makes date sorting fragile
 * (bug 19445) Change oldimage table to use ON UPDATE CASCADE for FK to image table.
 * (bug 14080) Short notation links to subpages didn't work in edit summaries
 * (bug 17374) Special:Export no longer exports multiple copies of pages
 * (bug 19818) Edits to user CSS/JS subpages can now be marked as patrolled by users who can't edit them
 * (bug 19839) Comments in log items are no more double escaped
 * (bug 18161) Fix inconsistent separators in watchlist link toolbars with "enhanced recent changes"
 * (bug 16877) Moving a page over a redirect no longer leaves an orphan entry in the recentchanges table
 * (bug 16009) Limit selection forms based on Pager now links to the correct page when using long urls
 * The display of the language list on the preferences is more comply with the BCP 47 standards.
 * (bug 19849) Custom X-Vary-Options header now disabled unless is set
 * (bug 19301) Duplicates entries in, , and  are no more displayed on Special:ListGroupRights
 * (bug 18799) Special:Userlogin now handles correctly the returnto parameter to not link back to Special:Userlogout when user's language isn't the same as content's language
 * (bug 19479) Show proper error message when unable to connect to PostgreSQL database with username/password in MediaWiki's setup
 * (bugs 18407, 18409) Special:Upload is now listed on Special:Specialpages only if uploads are enabled and the user can access it
 * (bug 17988) Spaces before [[Category:]] links are no longer ignored
 * (bug 19957) All known-failing tests now marked disabled; added --run-disabled option to parser test suite to run disabled tests if desired.
 * (bug 16311) Make recent change flags (n/m/b) s instead of  s
 * (bug 15680) Split the edit tip message of user CSS/JS subpage into "usercssyoucanpreview" and "userjsyoucanpreview" respectively.
 * (bug 12110) Split the rights for editing users' CSS/JS subpage from "editusercssjs" into "editusercss" and edituserjs" respectively.
 * (bug 19394) RecentChanges feed URLs for log items with no revisions (eg Newuser, Userrights) are no longer broken
 * (bug 17395) Remote file descriptions use user language, not wiki language
 * (bug 11867) Lock error on redirect table when running orphans.php
 * (bug 18930) initStats.php now refreshes active users count
 * (bug 18699) Using the nosummary URL option no longer triggers the "You have not provided a summary" warning for those who activated it in their preferences
 * (bug 18855) commandLine.inc and Maintenance.php are now properly included using the full path
 * (bug 18497) Fixed broken style sheets in Opera fullscreen mode
 * (bug 16084) Default memory limit has be increased to 50M, see
 * (bug 17864/19519) Added proper input normalization in Special:UserRights
 * (bug 20086) Add Hook to add extra statistics at the end of Special:Statistics
 * (bug 19289) importDump.php can now handle bzip2 and 7zip
 * (bug 20131) Fixed a PHP notice for users having the "rollback" right on Special:RecentChangesLinked
 * Do not transform EXIF fields with pure text to avoid results like foo,bar@example,com
 * (bug 20176) Fix login/logout links in skin CologneBlue
 * (bug 20203) "Powered by Mediawiki" now has height/width on image tag
 * (bug 20273) Fix broken output when no pages are found in the content namespaces
 * (bug 20265) Make AncientPages and UnusedFiles work on SQLite
 * Fixed XSS vulnerability for Internet Explorer clients (only pre-release versions of MediaWiki were affected).
 * (bug 14817) Moving a page to a subpage of itself moves it twice
 * (bug 20289) should only count pages actually moved
 * (bug 15248) Non-breaking spaces and certain other Unicode space characters are now normalized to ordinary spaces in titles; if your wiki has existing titles with such characters, run cleanupTitles.php and/or cleanupImages.php
 * (bug 11143) Links containing invalid UTF-8 percent-code sequences are now cleanly disabled instead of breaking parsing entirely on PHP 5.2.
 * (bug 20296) Fixed an PHP warning in Language::getMagic in PHP 5.3
 * (bug 20358) Unprotect tab was missing accesskey; now same as protect tab.
 * (bug 20317) Cleaned up default main page link accesskey settings
 * (bug 20362) Special:Statistics now produces valid HTML when view counters are enabled
 * (bug 19857) maintenance/deleteRevision.php on last revision no longer breaks target page
 * (bug 20365) Page name with with c/g/h/j/s/u + x are now correctly handled in Special:MovePage with Esperanto as content language
 * (bug 20364) Fixed regression in GIF metadata loading
 * (bug 20299) MediaWiki:Move-subpages and MediaWiki:Move-talk-subpages can now use wikitext
 * (bug 15475) DatabaseBase::setFlag, DatabaseBase::clearFlag and DatabaseBase::getFlag now have documentation
 * (bug 19966) MediaWiki:License-header is now used for the licensing header in the file description page instead of MediaWiki:License
 * (bug 20380) Links to history/deleted edits at the top of Special:RevisionDelete are no more displayed when when doing log suppression
 * (bug 8143) Localised parser function names are now correctly case insensitive if they contain non-ASCII characters
 * (bug 19055) maintenance/rebuildrecentchanges.php now purges Special:Recentchanges's RSS and Atom feed cache
 * The installer will now try to bypass PHP's max_execution_time
 * (bug 20260) SQLite no longer tries to automatically create the database at execution time, this now happens only at install time; if it is not available at script execution, it now throws an exception
 * Fixed EditFilterMerged hook so the hookError parameter serves a purpose (analogous to EditFilter hook)
 * (bug 2257) Tag extensions can expand template parameters provided to the tag, by using a new parameter added to the recursiveTagParse function
 * (bug 14900) __INDEX__ and __NOINDEX__ no longer override site config set in.
 * (bug 20466) Hidden categories are no more displayed when printing
 * (bug 20446) When changing user rights with User@remotewiki and remotewiki is the local wiki, the user is now treated as the local user
 * (bug 20494) OutputPage::getArticleBodyOnly no longer requires an useless argument
 * (bug 20136) Protection form JavaScript now synchronizes the expiry boxes on any change, in addition to onkeyup.
 * Don't link to "edit this page" on MediaWiki:Noarticletext if user is not allowed to create page. Done via new message MediaWiki:Noarticletext-nopermission
 * Improved compatibility between the Vector skin and addPortletLink from wikibits.js: empty portlets are now present but hidden, adding an element to a portlet unhides it
 * (bug 19531) addPortletLink now wraps inserted labels in a  element to be compatible with the CSS for the Vector skin
 * (bug 20578) Wrong localized image metadata - duplicated string?
 * (bug 20556) Stub threshold's "other" in Special:Preferences now has a correct type="text" parameter
 * (bug 482) Don't include TOC in the printable version if it has been hidden
 * Adjust the time according to the user configuration on Special:Revisiondelete
 * (bug 20624) Installation no longer allows "qqq" as the chosen language
 * (bug 20634) The installer-created database user will now have all rights on the database so that upgrades will go more smoothly.
 * (bug 18180) Special:Export ignores limit, dir, offset parameters
 * User::getBlockedStatus works for all kinds of user objects and doesn't assume the user object is equal to the current-user object
 * (bug 20517) Cancel link from edit page now returns to the old version when editing an old version
 * (bug 16902) Installer no longer shows warnings when exec has been disabled by disable_functions
 * (bug 20726) Title::getLatestRevID's documentation now says that the function returns false if the page doesn't exist
 * (bug 20751) ForeignApiRepo now urldecodes filenames when saving to local cache
 * (bug 20730) Fix to Special:Version ViewVC link for branch checkouts
 * (bug 20353) wfShellExec was adding extra quotes on Windows Vista, causing command line scripts to fail
 * (bug 20702) Parser functions can now be used correctly in MediaWiki:Missing-article
 * (bug 14117) "redirected from" is now also shown on foreign file redirects
 * (bug 17747) Only display thumbnail column in file history if the image can be rendered.
 * (bug 3421) Live preview no longer breaks user CSS/JS previews
 * (bug 11264) The file logo on a file description page for documents (PDF, ...) now links to the file rather than the file description page
 * Password fields built with HTMLForm now still have the type="password" attribute if 5=false.
 * (bug 20836) Preload now works for MediaWiki namespace
 * (bug 20885) Search box no longer suggests unavailable special pages
 * (bug 20948) "Create this page" on Special:Search is no longer displayed when searching for special pages
 * (bug 20524) Hideuser: Show nice error when trying to block hidden user without hideuser right
 * (bug 21026) Fixed file redirects on shared repos on non-English client wikis
 * (bug 21030) Fixed schema choices from being overwritten by defining unique field names per driver.
 * (bug 21115) wgCanonicalSpecialPageName javascript variable is now always false on non-special pages
 * (bug 21113) "Other statistics" header on Special:Statistics is no more displayed when there isn't any entry in it
 * (bug 21114) Special:Contributions no longer shows diff links for new revisions
 * (bug 21116) MediaWiki:Templatesused, MediaWiki:Templatesusedpreview and MediaWiki:Templatesusedsection now support plural
 * (bug 21079) There is no more line wrapping between label and field in Special:Log
 * (bug 20256) Fixed SQL errors on Special:Recentchanges and Special:Recentchangeslinked on SQLite backend
 * (bug 20880) Fixed updater failure on SQLite backend
 * (bug 21182) Fixed invalid HTML in Special:Listgrouprights
 * (bug 20242) Installer no longer promts for user credentials for SQLite databases * (bug 20911) Installer failed to create a SQLite database
 * (bug 20847) Deprecated deprecated akeytt removed in wikibits.js leaving dummy
 * (bug 21161) Changing now always invalidates file cache
 * (bug 20268) Fixed row count estimation on SQLite backend
 * (bug 20275) Fixed LIKE queries on SQLite backend
 * (bug 21234) Moving subpages of titles containing \\ now works properly
 * (bug 21006) maintenance/updateArticleCount.php now works again on PostgreSQL
 * (bug 19319) Add activeusers-intro message at top of SpecialActiveUsers page
 * (bug 21255) Fixed hostname construction for DNSBL checking
 * (bug 18019) Users are now warned when moving a file to a name in use on a shared repository and only users with the 'reupload-shared' permission can complete the move.
 * (bug 18909) Add missing Postgres INSERT SELECT wrapper
 * User::isValidPassword now only returns boolean results, User::getPasswordValidity can be used to get an error message string
 * The error message shown in Special:ChangePassword now parses wiki markup
 * (bug 19859) Removed experimental HTMLDiff feature
 * Removed section edit links in edit conflict form
 * Allow SpecialActiveusers to work on non-MySQL databases
 * (bug 6579) Fixed protecting images from uploading only
 * (bug 18609) Search index was empty for some pages
 * (bug 13453) rebuildrecentchanges maintenance script works on PG again
 * (bug 16583) Reduce false positives when checking for PHP (on upload, etc.)
 * (bug 20112) Bitrotted tests in the t/ directory were failing.
 * (bug 21470) MediaWiki:Sp-contributions-explain is now wrapped in a  with id "mw-sp-contributions-explain"
 * (bug 19159) Fixed \overleftrightarrow in texvc
 * (bug 19391) Fix caching for Recent ChangesFeed.
 * (bug 21455) Fixed "Watch this page" checkbox appearing on some special pages even to non-logged in users
 * (bug 21551) Rewrote the Squid purge HTTP client to provide a more robust and general implementation of HTTP, allowing it to purge non-Squid caches such as Varnish.
 * Fixed corruption of long UDP debug log messages by using socket_sendto instead of fsockopen with fwrite.
 * (bug 16884) Fixed feed links in sidebar not complying with URL parameters of the displayed page
 * (bug 21403) memcached class renamed to MWMemecached to avoid conflict with PHP's memcached extension
 * (bug 21650) Both calls to SkinTemplateTabs hook are now compatible
 * (bug 21672) Add missing Accept-Language to both Vary and XVO headers
 * (bug 21679) "Edit block reasons" link at the bottom of Special:Blockip is now only displayed to the users that have "editinterface" right
 * (bug 21740) Attempting to protect a page that doesn't exist (salting) returns "unknown error"
 * (bug 18762) both redirects and links get fixed one after another if redirects-only switch is not present
 * (bug 20159) thumbnails rerendered if older that
 * Fixed a bug which in some situations causes the job queue to grow forever, due to an infinite loop of job requeues.
 * (bug 21523) File that can have multiple pages (djvu, pdf, ...) no longer have the page selector when they have only one page
 * (bug 21559) "logempty" message is now wrapped in a div with class "mw-warning-logempty" when used in log extract
 * (bug 20549) Parser tests were broken on SQLite backend
 * (bug 21776) Interwiki urls like http://en.wikibooks.org/wiki/cs: should give a redirect instead of a baderror.
 * (bug 21803) Special:MyContributions now keeps the query string parameters
 * Redirecting special pages now keep query string paramters set to "0" (e.g. for namespace)
 * (bug 20765) Special:ListGroupRights no longer misses addables and removables groups if there are duplicate entries
 * (bug 21814) Message shown when rolling back an edit with a deleted username now shows '(username deleted)' instead of broken user tool links
 * (bug 21536) Fixed JavaScript error on Special:Search caused by an incorrect ID
 * (bug 21535) RecentChanges RSS feed now always recognises the namespace filter, previously it sometimes didn't due to caching.
 * (bug 20388) ProfilerSimpleText no longer outputs comment on action=raw
 * refreshLinks.php now purges orphaned redirect table rows
 * (bug 2971) Swap links of hist & diff location on Special:Contributions for consistency with RC/WL
 * (bug 21986) Special page names were are now capitalized by content language
 * If two log type have the same description, they're now both displayed in the type selector on Special:Log
 * (bug 20115) Special:Userlogin title says "Log in / create account" even if the user can't create an account
 * (bug 2658) Don't attempt to set the TZ environment variable.
 * (bug 9794) User rights log entries for foreign user now links to the foreign user's page if possible
 * (bug 14717) Don't load nonexistent CSS fix files for non-Monobook skins
 * (bug 22034) Use wfClientAcceptsGzip in wfGzipHandler instead of reimplementing it.
 * (bug 19226) First line renders differently on many UI messages.
 * (bug 21303) Comments are no longer stripped from MediaWiki:Common.js and skin-specific JS pages
 * (bug 5061) Use the more precise thumbcaption thumbimage and thumbinner classes for image divs.
 * Fixed bug involving unclosed "-{" markup in the language converter
 * (bug 21870) No longer include Google logo from an external server on wiki error.
 * (bug 22181) Do not truncate if the ellipsis actually make the string longer
 * (bug 16039) Text disappearing after a bad image
 * (bug 18784) Internal links like Foo should read 'caption', not 'File:Foo' when Foo is not an image
 * (bug 21518) Special:UserRights no longer displays the user name box for users that can only change their rights
 * (bug 21593) Special:UserRights now lists automatic groups membership
 * (bug 22364) Setting to false no longer hides the reupload link from file pages
 * Fix bug introduced in MediaWiki 1.12: The author field in is no longer sorted with sort but rather used as it appears in extensions as was the case before r30117 where it was unintentionally sorted along with other fields.
 * (bug 19334) Textarea no longer jumps when editing longer articles in IE8
 * Truncate summary of page moves in revision comment field to avoid broken multibyte characters
 * (bug 22540) ForeignApiRepos no longer try to store thumbnails that don't exist
 * (bug 22551) Special:Resetpass now has a "Cancel" button that sends the user to the page set in the &returnto parameter.
 * (bug 19194) Search box in Modern skin doesn't focus with Safari/Chrome
 * (bug 17790) Users instantly logged off on HughesNet

API changes in 1.16

 * Added uiprop=changeablegroups to meta=userinfo
 * Added usprop=gender to list=users
 * (bug 18311) action=purge now works for images too
 * Add parentid to prop=revisions output
 * (bug 17832) action=delete returns 'unknownerror' instead of 'permissiondenied' when the user is blocked
 * (bug 18546) Added timestamp of new revision to action=edit output
 * (bug 18554) Also list hidden revisions in list=usercontribs for privileged users
 * (bug 13049) "API must be accessed from the primary script entry point" error
 * (bug 16422) Don't display help for format=jsonfm unless specifically requested
 * Added PHP and database version to meta=siteinfo output
 * (bug 18533) Add readonly message to meta=siteinfo output
 * (bug 18518) Add clprop=hidden to prop=categories
 * (bug 18710) Fixed internal error with empty parameter in action=paraminfo
 * (bug 18709) Missing descriptions for some parameters in action=paraminfo output
 * (bug 18731) Show correct SVN links for extension modules in api.php?version
 * (bug 18730) Add version information to action=paraminfo output
 * (bug 18743) Add ucprop=size to list=usercontribs
 * (bug 18749) Add generator flag to action=paraminfo output
 * Make action=block respect and
 * Made deleting file description pages without files possible
 * (bug 18773) Add content flag to siprop=namespaces output
 * (bug 18785) Add siprop=languages to meta=siteinfo
 * (bug 14200) Added user and excludeuser parameters to list=watchlist and list=recentchanges
 * Added index, fromtitle and byteoffset fields to action=parse&prop=sections output
 * (bug 19313) action=rollback returns wrong revid on master/slave setups
 * (bug 19323) action=parse doesn't return section tree on pages with Cite warnings
 * (bug 18720) Add anchor field to action=parse&prop=sections output
 * (bug 19423) The initial file description page used caption in user lang rather than UI lang
 * (bug 17809) Add number of users in user groups to meta=siteinfo
 * (bug 18533) Add readonly reason to readonly exception
 * (bug 19528) Added XSLT parameter to API queries in format=xml
 * (bug 19040) Fix prependtext and appendtext in combination with section parameter in action=edit
 * (bug 19090) Added watchlist parameter, deprecated watch and unwatch parameter in action=edit
 * Added fields to list=search output: size, wordcount, timestamp, snippet
 * Where supported by backend, list=search adds a 'searchinfo' element with optional info: 'totalhits' count and 'suggestion' alternate query term
 * (bug 19907) added to allow specified (or all) external domains to access api.php via AJAX, if the browser supports the Access-Control-Allow-Origin HTTP header
 * (bug 19999) Made metadata and properties of search results optional. Added srprop and srinfo.
 * (bug 20700) Add amprop=default to meta=allmessages to list default value for customized messages
 * Don't parse magic words in meta=allmessages, output messages unparsed
 * (bug 21105) list=usercontribs can now list contribs for User:0
 * (bug 21085) list=deletedrevs no longer returns only one revision when drcontinue param is passed
 * (bug 21106) Deprecated parameters now tagged in action=paraminfo
 * (bug 19004) Added support for tags
 * (bug 21083) list=allusers no longer returns current timestamp for users without registration date
 * (bug 20967) action=edit allows creation of invalid titles
 * (bug 19523) Add inprop=watched to prop=info
 * (bug 21589) API: Separate summary and initial page text for uploads
 * (bug 21817) list=usercontribs returns empty result for empty ucuser
 * (bug 21441) meta=userinfo&uiprop=options no longer returns default options for logged-in users under certain circumstances
 * (bug 21945) Add chomp control in YAML
 * Expand the thumburl to an absolute url to make it consistent with url and descriptionurl
 * (bug 20233) ApiLogin::execute doesn't handle LoginForm :: RESET_PASS
 * (bug 22061) API: add prop=headitems to action=parse
 * (bug 22240) API: include time in siteinfo
 * (bug 22241) Quick edit is still using the deprecated watch parameter (API: Setting default for watch/unwatch wrongly set)
 * (bug 22245) blfilterredirect=nonredirects in blredirect mode wrongly filtering
 * (bug 22248) Output extension URLs in meta=siteinfo&siprop=extensions
 * Support key-params arrays in 'descriptionmsg' in meta=siteinfo&siprop=extensions
 * (bug 21922) YAML output should quote asterisk when used as key
 * (bug 22297) safesubst: to allow substitution without breaking transclusion
 * (bug 18758) API read of watchlist's wl_notificationtimestamp
 * (bug 20809) Expose EditFormPreloadText via the API
 * (bug 18427) Comment (edit summary) parser option for API
 * (bug 18608) API should provide list of CSS styles to apply to rendered output
 * (bug 18771) List possible errors in action=paraminfo

Languages updated in 1.16
MediaWiki supports over 330 languages. Many localisations are updated regularly. Below only new and removed languages are listed, as well as changes to languages because of MediaZilla reports.


 * Capiznon (cps) (new)
 * North Frisian (frr) (new)
 * Kirmanjki (kiu) (new)
 * Komi-Permyak (koi) (new)
 * Karachay-Balkar (krc) (new)
 * Latgalian (ltg) (new)
 * Hill Mari (mrj) (new)
 * Prussian (prg) (new)
 * Romagnol (rgn) (new)
 * Rusyn (rue) (new)
 * Lower Silesian (sli) (new)
 * Picard (pcd) (new)
 * Uyghur (Arabic script) (ug-arab) (new)
 * Upper Franconian (vmf) (new)
 * Votic (vot) (new)
 * Eastern Yiddish (ydd) (removed)
 * Iriga Bicolano (bto) (removed)
 * Ladin (lld) (removed)
 * Palembang (plm) (removed)
 * Megleno-Romanian (Greek script) (ruq-grek) (removed)
 * Tamazight (tzm) (removed)


 * (bug 18474) Sorani (ckb - Central Kurdish) (renamed from ku-arab)
 * Add PLURAL function for Scots Gaelic (gd)
 * Add Estonian letters äöõšüž to linktrail (et)
 * (bug 18776) Native name of Burmese language (my)
 * (bug 18806) Use correct unicode characters in spelling of native Chuvash (???????)
 * (bug 18864) Updated autonym for Zhuang language
 * (bug 18308) Updated date formatting in Occitan (oc)
 * (bug 19080) Added aâîst??AÂÎST?? to Romanion (ro) linktrail
 * (bug 19286) Correct commafying function in Polish (pl)
 * (bug 19441) Updated date formatting for Lithuanian
 * (bug 19630) Added ÄäÇçGgNnÖöSsÜüÝýŽž to Turkmen (tk) linktrail
 * (bug 19949) New linktrail for Greek (el)
 * (bug 19809) Korean (North Korea) (ko-kp) (new)
 * (bug 19968) Fixed "Project talk" namespace name for Maltese (mt)
 * (bug 21168) Added áâãàéêçíóôõúü to Portuguese (pt) linktrail
 * (bug 21596) Change interwiki link for Kurdish (ku)

Compatibility
MediaWiki 1.16 requires PHP 5.1 (5.2 recommended). PHP 4 is no longer supported.

MySQL 3.23.x is no longer supported; some older hosts may need to upgrade. At this time we still recommend 4.0, but 4.1/5.0 will work fine in most cases.

Upgrading
1.16 has several database changes since 1.15, and will not work without schema updates.

If upgrading from before 1.11, and you are using a wiki as a commons repository, make sure that it is updated as well. Otherwise, errors may arise due to database schema changes.

If upgrading from before 1.7, you may want to run refreshLinks.php to ensure new database fields are filled with data.

If you are upgrading from MediaWiki 1.4.x or earlier, some major database changes are made, and there is a slightly higher chance that things could break. Don't forget to always back up your database before upgrading!

See the file UPGRADE for more detailed upgrade instructions.

Caveats
Some output, particularly involving user-supplied inline HTML, may not produce 100% valid or well-formed XHTML output. Testers are welcome to set = "application/xhtml+xml"; to test for remaining problem cases, but this is not recommended on live sites. (This must be set for MathML to display properly in Mozilla.)

For notes on 1.15.x and older releases, see HISTORY.

Online documentation
Documentation for both end-users and site administrators is currently being built up on MediaWiki.org, and is covered under the GNU Free Documentation License (except for pages that explicitly state that their contents are in the public domain) :

Documentation

Mailing list
A MediaWiki-l mailing list has been set up distinct from the Wikipedia wikitech-l list:

A low-traffic announcements-only list is also available: It's highly recommended that you sign up for one of these lists if you're going to run a public MediaWiki, so you can be notified of security fixes.
 * mediawiki-l
 * mediawiki-announce

IRC help
There's usually someone online in the IRC channel.