Release notes/1.22

Security reminder: MediaWiki does not require PHP's register_globals. If you have it on, turn it off if you can.

MediaWiki 1.22.1
This is a security and maintenance release of the MediaWiki 1.22 branch.

Changes since 1.22.0

 * SECURITY: Disallow stylesheets in SVG Uploads
 * SECURITY: Don't normalize U+FF3C to \ in CSS Checks
 * SECURITY: Disallow -o-link in styles
 * SECURITY: Return error on invalid XML for SVG Uploads
 * SECURITY: Fix RevDel log entry information leaks
 * Restore compatibility with curl < 7.16.2.
 * Updated the plural rules to CLDR 24. They are in new format which is detailed in UTS 35 Rev 33. The PHP parser and evaluator as well as the JavaScript evaluator were updated to support the new format. Plural rules for some languages have changed, most notably Russian. Affected software messages have been updated and marked for review at translatewiki.net. This change is backported from the development branch of MediaWiki 1.23.
 * The broken installer for database backend Oracle was fixed.
 * The web installer no longer throws an exception when PHP is compiled without support for MySQL yet with support for another DBMS.
 * Fixed a compatibility issue with PCRE 8.34 that caused pages to appear blank or with missing text.
 * Changed FOR UPDATE handling in Postgresql
 * Avoid extra parsing in prepareContentForEdit

MediaWiki 1.22.0
MediaWiki 1.22.0 is the stable branch and is recommended for use in production. MediaWiki 1.22.0 is a large release that contains many new features and bug fixes.
 * Breaking Changes in 1.22.0
 * New features in 1.22.0
 * Configuration changes in 1.22.0
 * Bug fixes in 1.22.0
 * API changes in 1.22.0
 * Languages updated in 1.22.0
 * Other changes in 1.22.0

Breaking changes

 * Display editsection links next to headings. Also change their class name from .editsection to .mw-editsection and place them at the end of the heading element instead of the beginning. Client-side code and screen-scrapers will have to be adjusted to handle both cases (old HTML will still be visible on cached page renders until they are purged); extensions using the DoEditSectionLink or EditSectionLink hooks might need adjustments as well.
 * Removed undocumented 'Debug' hook in wfDebug. This resolves an infinite loop when using $wgDebugFunctionEntry = true.
 * action=parse no longer returns all langlinks for the page with prop=langlinks by default. The new effectivelanglinks parameter will request that the LanguageLinks hook be called to determine the effective language links.
 * list=allpages, list=langbacklinks, and prop=langlinks do not apply the new LanguageLinks hook, and thus only consider language links stored in the database.
 * Implementation of MediaWiki's JS and JSON value encoding has changed:
 * MediaWiki no longer supports PHP installations in which the native JSON extension is missing or disabled.
 * XmlJsCode objects can no longer be nested inside objects or arrays. (For Xml::encodeJsCall, this individually applies to each argument.)
 * The sets of characters escaped by default, along with the precise escape sequences used, have changed (except for the Xml::escapeJsString  function, which is now deprecated).
 * The Services_JSON class has been removed. If necessary, be sure to upgrade affected extensions at the same time (e.g. Collection).
 * Legacy skins Simple, MySkin, Chick, Standard and Nostalgia were all removed. (Nostalgia was moved to an extension.) The SkinLegacy and LegacyTemplate classes that supported them were removed as well and are now a part of the Nostalgia extension.
 * The "ExternalAuth" authentication subsystem was removed, along with its associated globals of $wgExternalAuthType, $wgExternalAuthConf, $wgAutocreatePolicy and $wgAllowPrefChange. Affected users are encouraged to use AuthPlugin for external authentication/authorization needs.
 * mw.util.tooltipAccessKeyRegexp: The match group for the accesskey character is now $6 instead of $5.
 * meta keywords are no longer supported. A &lt;meta name="keywords" will no longer be output and OutputPage::addKeyword no longer exists.
 * The EditSectionLink hook was removed after being deprecated since MediaWiki 1.14. Use DoEditSectionLink instead.
 * wikibits: Drop support for mwCustomEditButtons. It defaults to an empty array and emits mw.log.warn when accessed.
 * Special:Disambiguations has been removed from MediaWiki core. Functions related to disambiguation pages are now handled by the Disambiguator extension (https://www.mediawiki.org/wiki/Extension:Disambiguator).
 * The 'mediawiki.legacy.wikiprintable' module has been removed. The skins/common/wikiprintable.css file no longer exists. Return value of Skin#commonPrintStylesheet is ignored. Please use the 'mediawiki.legacy.commonPrint' module instead or base your skin on SkinTemplate.
 * The module 'mediawiki.legacy.IEFixes' has been removed as it was unused. The file skins/common/IEFixes.js remains but is only used by wikibits. The file never contained any re-usable components. To use it in a skin, load 'mediawiki.legacy.wikibits' (which IEFixes depends on) and that will import IEFixes automatically if user agent conditions are met.

New features

 * You can now install extensions using Composer. See https://www.mediawiki.org/wiki/Composer
 * mediawiki.jqueryMsg can now parse (whitelisted) HTML elements and attributes.
 * Language::sprintfDate now has a timezone parameter, and supports the "eIOPTZ" formatting characters.
 * EditWarning: A warning is shown when an editor leaves the edit form without saving (enabled by default, users can opt-out via the 'useeditwarning' preference). This feature was moved from the Vector extension, and is now part of core for all skins. Take care when upgrading that you don't use an older version of the Vector extension as this feature may conflict.
 * New 'mediawiki.ui' CSS module providing mw-ui-* styles for buttons and a compact vertical form layout.
 * HTMLForm supports a new display format 'vform' which applies this compact vertical layout and button styling. Special:PasswordReset uses this format.
 * New versions of login (Special:UserLogin) and create account (Special:UserLogin/signup) forms using the "vform" compact vertical form layout. These forms use new messages that assume a "Help logging in" link, see https://www.mediawiki.org/wiki/Manual:Page_customizations; https://www.mediawiki.org/wiki/Account_creation_user_experience/Strings lists the message key changes.
 * Implemented ability to apply IP blocks to the contents of X-Forwarded-For headers by adding a new configuration variable $wgApplyIpBlocksToXff (disabled by default).
 * The new hook 'APIGetPossibleErrors' to modify the list of possible errors was added.
 * LogEventsList::showLogExtract will now ignore various Pager-related WebRequest parameters by default, as this is overwhelmingly likely to be what was intended by users of the method. If any caller wishes to use these parameters, the new param 'useRequestParams' may be set to true.
 * mw.util.addPortletLink: Tooltip is no longer required to be plain (without an accesskey in it already). As such it now rountrips. Creating a link with a message as tooltip, grabbing the title attribute and using it to create another portlet will work as expected.
 * introduced, contains the name of the topmost page without namespace.
 * introduced the new 'LanguageLinks' hook for manipulating the language links associated with a page before display.
 * Chosen (http://harvesthq.github.io/chosen/) was added as module 'jquery.chosen'
 * HTMLForm will turn multiselect checkboxes into a Chosen interface when setting cssclass 'mw-chosen'
 * rebuildLocalisationCache learned --lang option. Let you rebuild l10n caches of the specified languages instead of all of them.
 * New GetNewMessagesAlert hook allowing extensions to disable or modify the new messages alert
 * New wgUserNewMsgRevisionId JS global for logged in users. This will be null if the user has no new talk page messages. Otherwise it will be set to the revision ID of the oldest new talk page message. This will allow gadgets and extensions to create their own new message alerts on the client side.
 * mediawiki.log: Added log.warn wrapper (uses console.warn and console.trace).
 * mediawiki.log: Implemented log.deprecate. This method defines a property and uses ES5 getter/setter to emit a warning when they are used.
 * $wgCascadingRestrictionLevels was added, allowing one to specify restriction levels which can be cascading (previously 'sysop' was hard-coded as the only one).
 * XHTML5 support has been improved. If you set $wgMimeType = 'application/xhtml+xml' MediaWiki will try outputting markup acording to XHTML5 rules.
 * Altered hook 'ProtectionForm::save', adding the reason page protection is changed as third parameter.
 * New hook 'TitleSquidURLs' for manipulating the list of URLs to be purged from HTTP caches when a page is changed.
 * Changed the patrolling system to always show the link for patrolling in case the current revision is patrollable. This also removed the usage of the rcid URI parameters.
 * Oracle DB backend now supports Database Resident Connection Pooling (DRCP). Can be enabled by setting $wgDBOracleDRCP=true. Requires Oracle DB 11gR1 or above, enabled DRCP inside the DB itself and a propper connect string. More about DRCP can be found at: http://www.oracle-base.com/articles/11g/database-resident-connection-pool-11gr1.php
 * Add a new parameter $patrolFooterShown to hook ArticleViewFooter so the hook handlers can take further action based on the status of the patrol footer
 * A new hook TitleQuickPermissions was added to allow overriding of quick permissions in the Title class.
 * LinkCache singleton can now be altered or cleared, letting one to specify another instance that does not rely on a database backend.
 * MediaWiki's PHPUnit tests can now use PHPUnit installed using composer --dev.
 * The lists of templates used on the page and hidden categories it is a member of, shown below the edit form, are now collapsible (and collapsed by default).
 * Parser profiling data, formerly only available in the "NewPP limit report" HTML comment, is now also displayed at the bottom of page previews.
 * Added ParserLimitReportPrepare and ParserLimitReportFormat hooks, deprecated ParserLimitReport hook.
 * New user rights have been added to increase granularity in rights management for extensions such as OAuth:
 * editmyusercss controls whether a user may edit their own CSS subpages.
 * editmyuserjs controls whether a user may edit their own JS subpages.
 * viewmywatchlist controls whether a user may view their watchlist.
 * editmywatchlist controls whether a user may edit their watchlist.
 * viewmyprivateinfo controls whether a user may access their private information (e.g. registered email address, real name).
 * editmyprivateinfo controls whether a user may change their private information.
 * editmyoptions controls whether a user may change their preferences.
 * Add new hook AbortTalkPageEmailNotification, this will be used to determine whether to send the regular talk page email notification
 * Action classes registered in $wgActions are now also supported in the form of a callback (which returns an instance of Action) instead of providing the name of a subclass of Action.
 * Vector: Add the collapsibleTabs script from the Vector extension.
 * Added $wgRecentChangesFlags for defining new flags for RecentChanges and watchlists.
 * mw.toolbar: Implemented mw.toolbar.addButtons for adding multiplebutton objects in one call.
 * Rights used for the default protection levels ('sysop' and 'autoconfirmed') are now used just for that purpose, instead of overloading other rights. This allows easy granting of the ability to edit sysop-protected pages without also granting the ability to protect and unprotect.
 * Make brackets in section edit links accessible to CSS. They are now wrapped in &lt;span class="mw-editsection-bracket" />.
 * Allow handler specific parameters in galleries (like page number)
 * jquery.client: Add detection for Opera 15 and Internet Explorer 11.
 * Change tags (used by the AbuseFilter extension) are now shown on diff pages.
 * Change tag lists (shown on recent changes, watchlist, user contributions, history pages, diff pages) now include a link to Special:Tags to distinguish them from edit summaries.
 * Added a new method and hook, User::isEveryoneAllowed and UserIsEveryoneAllowed, for use in situations where a "does everyone have this right?" check is used to avoid more expensive checks.
 * Display "(No difference)" instead of an empty diff (when comparing revisions in the history or when previewing changes while editing).
 * New hook 'IsUploadAllowedFromUrl' is added which can be used to intercept uploads by URL, useful for blacklisting specific URLs
 * Watchlist token implementation has been refactored and Special:ResetTokens was added to allow users to reset their tokens instead of presenting them in Preferences.
 * Special:PrefixIndex now lets you strip the searched prefix from the displayed titles. Given a list of articles named Bug1, Bug2, you can now transclude the list of bug numbers using: . The special page form received a new checkbox matching that option.
 * Implement javascript callback interface "mw.hook".
 * New mw.hook "wikipage.content".
 * jquery.placeholder gets a new parameter to set the attribute value to be used.
 * $wgHTCPMulticastRouting renamed $wgHTCPRouting since it accepts unicast.
 * $wgHTCPRouting rules can now be passed an array of hosts/ports to send purge too. Can be used whenever several multicast group could be interested by a specific purge.
 * Add Special:RandomInCategory.
 * mediawiki.util: addPortletLink now supports passing a jQuery object as nextnode.
 * &lt;wbr> can now be used inside WikiText.
 * WebResponse::setcookie is much more featureful. Callers using PHP's setcookie or setrawcookie should begin using this instead.
 * New hook WebResponseSetCookie, called from WebResponse::setcookie.
 * New hook ResetSessionID, called when the session id is reset.
 * Add a mode parameter to &lt;gallery> tag with potential options of "traditional", "nolines", "packed", "packed-overlay", or "packed-hover".
 * A success message is now displayed after changing the password.
 * Make thumb.php give HTTP redirects for file redirects
 * Special:ListFiles can now show old versions of files. Additionally Special:AllMyUploads was introduced so the user can get a list of all things they have ever uploaded, even if it was subsequently overriden.
 * Introduced Special:MyFiles and Special:AllMyFiles as an alias for Special:MyUploads and Special:AllMyUploads respectively.
 * IPv6 addresses in X-Forwarded-For headers are now normalised before checking against allowed proxy lists.
 * Add deferrable update support for callback/closure.
 * Add TitleMove hook before page renames.
 * Revision deletion backend code is moved out of SpecialRevisiondelete
 * Added variable to get the current size of a revision.
 * Add support for the LESS stylesheet language to ResourceLoader. LESS is a stylesheet language that compiles into CSS. ResourceLoader file modules may include LESS style files; ResourceLoader will compile these files into CSS before sending them to the client.
 * The $wgResourceLoaderLESSVars configuration variable is an associative array mapping variable names to string CSS values. These variables are considered  declared for all LESS files. Additional variables may be registered by  adding keys to the array.
 * $wgResourceLoaderLESSFunctions is an associative array of custom LESS function names to PHP callables. See &lt;http://leafo.net/lessphp/docs/#custom_functions>  for more details regarding custom functions.
 * $wgResourceLoaderLESSImportPaths is an array of file system paths. Files referenced in LESS '@import' statements are looked up here first.
 * ResourceLoader supports hashes as module cache invalidation trigger (instead of or in addition to timestamps).
 * Added $wgExtensionEntryPointListFiles for use in mergeMessageFileList.php.
 * Added a hook, APIQuerySiteInfoStatisticsInfo, to allow extensions to modify the output of the API query meta=siteinfo&siprop=statistics
 * Primary keys have been added to both the archive table and the externallinks tables.
 * Added $wgEnableParserLimitReporting to control whether the NewPP limit report is output in a HTML comment.
 * The 'UnwatchArticle' and 'WatchArticle' hooks now support a Status object instead of just a boolean return value to abort the hook.
 * Added a hook, SpecialWatchlistGetNonRevisionTypes, to allow extensions with custom recentchanges entries to hook into the Watchlist without clobbering each other.
 * A hidden, empty input field was added to the edit form, and any edit that fills it in will be rejected. This prevents against the simplest form of spambots. Previously in the "SimpleAntiSpam" extension by Ryan Schmidt.
 * populateRevisionLength.php maintenance script updated to also populate archive.ar_len field.
 * DatabaseMySQLBase learned to list views, optionally filtered by a prefix. Also fixed PHPUnit test suite when using a MySQL backend containing views.

Configuration changes

 * $wgRedirectScript was removed. It was unused.
 * Removed $wgLocalMessageCacheSerialized, it is now always true.
 * $wgVectorUseIconWatch is now enabled by default.
 * $wgCascadingRestrictionLevels was added.
 * ftps, ssh, sftp, xmpp, sip, sips, tel, sms, bitcoin, magnet, urn, and geo have been whitelisted inside of $wgUrlProtocols.
 * $wgDocType and $wgDTD have been removed and are no longer used for the DOCTYPE.
 * $wgHtml5 is no longer used by core. Setting it to false will no longer disable HTML5. It is still set to true for extension compatibility but doing so in extensions is deprecated.
 * $wgXhtmlDefaultNamespace is no longer used by core. Setting it will no longer change the xmlns used by MediaWiki. Reliance on this variable by extensions is deprecated.
 * $wgHandheldStyle was removed.
 * $wgHandheldForIPhone was removed.
 * $wgJsMimeType is no longer used by core. Most usage has been removed since HTML output is now exclusively HTML5.
 * $wgDBOracleDRCP added. True enables persistent connection with DRCP on Oracle.
 * $wgLogAutopatrol added to allow disabling logging of autopatrol edits in the logging table. default for $wgLogAutopatrol is true.
 * The 'edit' right no longer allows for editing a user's own CSS and JS.
 * New rights 'editmyusercss', 'editmyuserjs', 'viewmywatchlist', 'editmywatchlist', 'viewmyprivateinfo', 'editmyprivateinfo', and 'editmyoptions' restrict actions that were formerly allowed by default. They have been added to the default for $wgGroupPermissions['*'].
 * The 'editprotected' right no longer allows bypassing of all page protection restrictions. Any group using it for this purpose will now need to have all the individual rights listed in $wgRestrictionTypes for the same effect.
 * The 'protect' and 'autoconfirmed' rights are no longer used for the default page protection levels. The rights 'editprotected' and 'editsemiprotected' are now used for this purpose instead.
 * wgOldChangeTagsIndex removed.
 * $wgNoFollowDomainExceptions now only matches entire domains. For example, an entry for 'bar.com' will still match 'foo.bar.com' but not 'foobar.com'.
 * $wgCopyUploadTimeout and $wgCopyUploadAsyncTimeout added to change the timeout times for fetching the file during upload by url.
 * New key added to $wgGalleryOptions - $wgGalleryOptions['mode'] to set default gallery mode.
 * New hook 'GalleryGetModes' to allow extensions to make new gallery modes.
 * The checkbox for staying in HTTPS displayed on the login form when $wgSecureLogin is enabled has been removed. Instead, whether the user stays in HTTPS will be determined based on the user's preferences, and whether they came from HTTPS or not.
 * $wgRC2UDPAddress, $wgRC2UDPInterwikiPrefix, $wgRC2UDPOmitBots, $wgRC2UDPPort, and $wgRC2UDPPrefix configuration options have been deprecated in favor of a $wgRCFeeds configuration array. $wgRCFeeds makes both the format and destination of recent change notifications customizable, and allows for multiple destinations to be specified.
 * portal-url, currentevents-url and helppage have been removed from the default Sidebar.
 * The 'vector-simplesearch' preference is now enabled by default. Previously it was only enabled if the Vector extension was installed.
 * The precise format of metric datagrams produced by the UDP profiler and stats counter may now be specified as $wgUDPProfilerFormatString and $wgStatsFormatString, respectively.
 * $wgBlockOpenProxies, $wgProxyPorts, $wgProxyScriptPath, and $wgProxyMemcExpiry have been removed, along with the open proxy scanner script they were added for.
 * Default value of $wgMaxShellMemory has been tripled (it's now 300 MB).

Bug fixes

 * Disable Special:PasswordReset when $wgEnableEmail is false. Previously one could still navigate to the page by entering the URL directly.
 * Fixed a fatal error when a blocked user tries to automatically create an account on login due external authentication in some circumstances.
 * HTML &lt;hN> headings containing line breaks are now handled correctly.
 * Whitespace within == Headline == syntax and within &lt;hN> headings is now non-significant and not preserved in the HTML output.
 * Special:BlockList now handles correctly user names with spaces when passed as subpage.
 * Pager's properly validate which fields are allowed to be sorted on.
 * mw.util.tooltipAccessKeyRegexp: The regex now matches "option-" as well. Support for Mac "option" was added in 1.16, but the regex was never updated.
 * Usernames of blocking users now display correctly, even if numeric.
 * Self-transclusions now show the most up to date result always after save instead of being a revision behind.
 * A bias in wfRandomString toward digits 1-7 has been corrected. Generated strings will now start with digits 0 and 8-f as often as they should.
 * Removed Parser_LinkHooks and CoreLinkFunctions classes.
 * Allow &lt;kbd>, &lt;samp>, and &lt;var> to be nested like allowed in html.
 * PLURAL magic word no longer causes a PHP notice when no matching form exists.
 * Patrol page links no longer show on non-existent revisions.
 * Pages not linked from Special:RecentChanges or Special:NewPages are patrollable now.
 * JavaScript for search suggestions is now disabled when the API is disabled, and AJAX patrolling and watching are now disabled when use of the write API is not allowed.
 * API: Fix chunk upload async mode.
 * Broken files tracking category removed from pages if an image with that name is uploaded.
 * System messages that are empty were previously incorrectly treated as non-existent, causing a fallback to the default. This stopped users from overriding system messages to make them blank.
 * action=parse no longer returns an error if passed none of 'oldid', 'pageid', 'page', 'title', and 'text' (e.g. if only passed 'summary'). A warning will instead be issued if 'title' is non-default, unless no props are requested.
 * Special:Recentchangeslinked will now include upload log entries
 * Fixed ugly output if file size could not be extracted for multi-page media.
 * list=logevents API module will now output log entries by anonymous users.
 * Handle headers with rowspan in jquery.tablesorter
 * Converted the table of contents on wiki pages from &lt;table> to &lt;div> and adjusted skin CSS accordingly. The CSS was carefully crafted to be backwards-compatible in all reasonable cases (uses of the magic word, the #toc CSS id and the .toc CSS class). However, particularly bad abuse of the id or the class can possibly break.
 * CSSJanus now supports rgb, hsl, rgba, and hsla color syntaxes.
 * Special:Listfiles can no longer be sorted by image name when filtering by user in miser mode.
 * CSSJanus: Handle values of border-radius correctly.
 * Handle relative inclusions in main namespace with subpages enabled correctly (previously MediaWiki tried to include Template:Parent/name instead of just Parent/name).
 * Added $wgAPIUselessQueryPages to allow extensions to flag their query pages for non-inclusion in ApiQueryQueryPages.
 * mediawiki.notification: Notification area should remain visible when scrolled down.
 * Special:MIMESearch no longer an expensive special page.
 * Fixed a fatal error when $wgValidateAllHtml is set to true and the function apache_request_headers function is not available.
 * LivePreview: Re-run wikipage content handlers (jquery.makeCollapsible, jquery.tablesorter) after preview content is loaded.
 * Fixed PHP notice on Special:PagesWithProp when no properties are defined.
 * Corrected documentation of $wgTranscludeCacheExpiry.
 * The APIEditBeforeSave hook is giving the content of the whole revision as second argument now, rather than just the current section.
 * $wgSpamRegex is now also applied on the new section headline text adding a new topic on a page
 * Improve treatment of multiple comments on a blank line.
 * Purge upstream caches when deleting file assets.
 * File types with a mime that we do not know the extension for can no longer be uploaded as an extension that we do know the mime type for.
 * Add data-sort-value for better sorting of hitcounts Special:Tags
 * On DB error pages, server hostnames are now hidden when both $wgShowHostnames and $wgShowSQLErrors are false.
 * line breaks in &lt;blockquote> are handled like they are in &lt;div>
 * Default character set now set to 'utf8' when a new MySQL database is created.
 * Fixed "Column 'si_title' cannot be part of FULLTEXT index" MySQL error when installing using the binary character set option.
 * Support mysqli PHP extension
 * Correct tooltip of "Next n results" on query special pages.
 * mw.util.addPortletLink: Check length before access array index.
 * Logging in with a temporary password is no longer broken when $wgSecureLogin is true.

API changes

 * The JSON output formatter now leaves forward slashes unescaped to improve human readability of URLs and similar strings. Also, a "utf8" option is now provided to use UTF-8 encoding instead of hex escape codes for most non-ASCII characters.
 * xmldoublequote parameter was removed. Because of a bug, the parameter has had no effect since MediaWiki 1.16, and so its removal is unlikely to impact existing clients.
 * action=query&meta=siteinfo&siprop=skins will now indicate which skin is the default and which are unusable (e.g. listed in $wgSkipSkins).
 * Added support for wlshow filtering (bots/anon/minor/patrolled) to action=feedwatchlist.
 * WDDX formatted output will actually be formatted (and normal output will no longer be), and will no longer choke on booleans.
 * action=opensearch no longer silently ignores the format parameter.
 * action=opensearch now supports format=jsonfm.
 * list=usercontribs&ucprop=ids will now include the parent revision id.
 * Allow specifying change type of Wikipedia feed items
 * prop=imageinfo now allows setting iiurlheight without setting iiurlwidth
 * prop=info now adds the content model and page language of the title.
 * New upload log entries will now contain information on the relevant image (sha1 and timestamp).
 * action=parse now can parse in preview and section preview modes.
 * action=patrol now accepts revision ids.
 * list=blocks&bkip= now correctly handles IPv6 CIDR ranges and honors $wgBlockCIDRLimit. Note any clients passing invalid values to bkip will now receive an error, rather than the previous behavior listing all user blocks.
 * action=parse&text=foo now assumes wikitext if no title is given, rather than using the content model of the page "API".
 * action=watch no longer silently ignores hook abort.
 * action=purge with forcelinkupdate=1 no longer queues refreshLinks jobs in the job queue for link table updates of pages that use the given page as a template. Instead, forcerecursivelinkupdate=1 is introduced and should be used if that behaviour is desirable.
 * The 'debugLog' property (enabled by $wgDebugToolbar) no longer sets the log entry values through ApiResult::content but directly. This changes the JSON output from an array of objects with content in '*' to an array of strings with the content.
 * prop=imageinfo iicontinue now contains the dbkey, not the text version of the title.
 * action=edit will now use empty text instead of the contents of section 0 when passed prependtext or appendtext with section=new.
 * Support for the 'gettoken' parameter to action=block and action=unblock, deprecated since 1.20, has been removed.
 * Token-getting functions will fail when using jsonp callbacks.
 * action=upload returns normalized file name on warning "exists-normalized" instead of filename to be uploaded to.
 * action=edit will now return an error when the specified section does not exist in the page.
 * Added meta=filerepoinfo API module for getting information about foreign file repositories, and related ForeignAPIRepo methods getInfo and getApiUrl.
 * The new query module list=allfileusages to enumerate file usages was added.

Languages updated
MediaWiki supports over 350 languages. Many localisations are updated regularly. Below only new and removed languages are listed, as well as changes to languages because of Bugzilla reports.
 * Plural rules were updated to those from CLDR 24 for Manx (gv).
 * Explicit plural forms now work for Russian.
 * Explicit plural forms for languages that use a custom implementation for Language::convertPlural now work correctly.
 * Batak Toba (bbc-latn) added.
 * Made Buryat (Russia) (буряад) (bxr) fallback to Russian.

Other changes

 * redirect.php was removed. It was unused.
 * ClickTracking integration was dropped from the mediaWiki.user.bucket JavaScript function. The 'tracked' option is now ignored.
 * Event namespace used by jquery.makeCollapsible has been changed from 'mw-collapse' to 'mw-collapsible' for consistency with the module name.
 * The Quickbar feature of the legacy skin model and the last remnants of it throughout the code base have been removed.
 * Externaledit/externaldiff preference was removed. Very few users used this feature, and improper configuration can actually prevent a user from editing
 * Calling Linker methods using a skin will now output deprecation warnings.
 * "Return to" links are no longer tagged with rel="next".
 * HipHop compiler (hphpc) support was removed. HipHop VM support (hhvm) was added.
 * A new Special:Redirect page was added, providing lookup by revision ID, user ID, or file name. The old Special:Filepath page was reimplemented to redirect through Special:Redirect.
 * Monobook: Removed the old conditional stylesheets for Opera 6, 7 and 9.
 * Support for XHTML 1.0 has been removed. MediaWiki now only outputs (X)HTML5.
 * wikibits: User-agent related globals have been deprecated. The following properties now default to false and emit mw.log.warn: is_gecko, is_chrome_mac, is_chrome, webkit_version, is_safari_win, is_safari, webkit_match, is_ff2, ff2_bugs, is_ff2_win, is_ff2_x11, opera95_bugs, opera7_bugs, opera6_bugs, is_opera_95, is_opera_preseven, is_opera, and ie6_bugs.
 * MediaWiki will now flash a confirmation message upon successfully editing a page.
 * mediawiki.legacy.ajax has been marked as deprecated. The following properties now emit mw.log.warn when accessed: sajax_debug, sajax_init_object, sajax_do_call and wfSupportsAjax.
 * Methods Title::userCanEditCssSubpage and Title::userCanEditJsSubpage, deprecated since 1.19, have been removed.
 * Hook functions are no longer required to return a value. When a hook function does not return a value (or when it returns an explicit null), processing continues. To abort the hook, a hook function must return an explicit, boolean false or a string error message. Other falsey values are tantamount to a 'return true' in earlier versions of MediaWiki.
 * The 'editsection-brackets' optional message was removed. Section edit links' brackets can now be customized using CSS by styling span.mw-editsection-bracket.
 * The usePatrol function in ChangesList has been marked as deprecated.
 * A "null edit", that is, a save action in which no changes to the page text are made and no revision recorded, will no longer send refreshLinks jobs to the job table to update pages which use the edited page as a template.
 * The LivePreviewPrepare and LivePreviewDone events triggered on "jQuery( mw )" have been deprecated in favour of using mw.hook.
 * The 'showjumplinks' user preference has been removed, jump links are now always included.
 * Methods RecentChange::notifyRC2UDP, RecentChange::sendToUDP, and RecentChange::cleanupForIRC have been deprecated, as it is now the responsibility of classes implementing the RCFeedFormatter and RCFeedEngine interfaces to implement the formatting and delivery for recent change notifications.
 * SpecialPrefixindex methods namespacePrefixForm and showPrefixChunk have been made protected. They were accepting form variance arguments, this is now using properties in the SpecialPrefixindex class.
 * The hook ExtractThumbParamaters has been deprecated in favour of media handler overriding MediaHandler::parseParamString.
 * The collapsibleNav feature from the Vector extension has been moved to the Vector skin in core.
 * SpecialRecentChanges::addRecentChangesJS function has been renamed to addModules and made protected.
 * Methods WatchAction::doWatch and WatchAction::doUnwatch now return a Status object instead of a boolean.
 * Information boxes (CSS classes errorbox, warningbox, successbox) have been made more subtle.
 * Code specific to the Math extension was marked as deprecated.
 * mediawiki.util: mw.util.wikiGetlink has been renamed to getUrl. (The old name still works, but is deprecated.)

Compatibility
MediaWiki 1.22 requires PHP 5.3.2 or later.

MySQL is the recommended DBMS. PostgreSQL or SQLite can also be used, but support for them is somewhat less mature. There is experimental support for Oracle.

The supported versions are:


 * MySQL 5.0.2 or later
 * PostgreSQL 8.3 or later
 * SQLite 3.3.7 or later
 * Oracle 9.0.1 or later

Upgrading
1.22 has several database changes since 1.21, and will not work without schema updates. Note that due to changes to some very large tables like the revision table, the schema update may take quite long (minutes on a medium sized site, many hours on a large site).

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, you should upgrade to 1.5 first. The upgrade script maintenance/upgrade1_5.php has been removed with MediaWiki 1.21.

Don't forget to always back up your database before upgrading!

See the file UPGRADE for more detailed upgrade instructions.

For notes on 1.21.x and older releases, see HISTORY.

Online documentation
Documentation for both end-users and site administrators is available 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):

https://www.mediawiki.org/wiki/Documentation

Mailing list
A mailing list is available for MediaWiki user support and discussion:

https://lists.wikimedia.org/mailman/listinfo/mediawiki-l

A low-traffic announcements-only list is also available:

https://lists.wikimedia.org/mailman/listinfo/mediawiki-announce

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.

IRC help
There's usually someone online in #mediawiki on irc.freenode.net.