Release notes/1.34

= MediaWiki 1.34 =

THIS IS NOT A RELEASE YET

MediaWiki 1.34 is an pre-release testing branch, and is not recommended for use in production.

Changes since MediaWiki 1.34.0-rc.0

 * (T231742) rdbms: Restore debug toolbar "Queries" feature.

Upgrading notes for 1.34
1.34 has several database changes since 1.33, 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).

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

See the file UPGRADE for more detailed upgrade instructions, including important information when upgrading from versions prior to 1.11.

Some specific notes for MediaWiki 1.34 upgrades are below:


 * MediaWiki now requires PHP 7.2.9 or above.
 * MediaWiki no longer supports HHVM.

For notes on 1.33.x and older releases, see HISTORY.

Configuration changes for system administrators in 1.34
In an effort to enforce best practices for passwords, MediaWiki will now warn users, and suggest that they change their password, if it is in the list of 100,000 commonly used passwords that are considered bad passwords. If you want to disable this for your users, please add the following to your local settings:

$wgPasswordPolicy['policies']['default']['PasswordNotInLargeBlacklist'] = false;

New configuration

 * $wgAllowExternalReqID (T201409) - This configuration setting controls whether Mediawiki accepts the request ID set by the incoming request via the `X-Request-Id` header. If set to `true`, that value will be used throughout the code as the request identificator. Otherwise, the sent header will be ignored and the request ID will either be taken from Apache's mod_unique module or will be generated by Mediawiki itself (depending on the set-up).
 * $wgEnableSpecialMute (T218265) - This configuration controls whether Special:Mute is available and whether to include a link to it on emails originating from Special:Email.
 * editmyuserjsredirect user right – users without this right now cannot edit JS redirects in their userspace unless the target of the redirect is also in their userspace. By default, this right is given to everyone.
 * (T226733) Add rate limiter to Special:ConfirmEmail.

Changed configuration

 * $wgUseCdn, $wgCdnServers, $wgCdnServersNoPurge, and $wgCdnMaxAge – These four CDN-related config variables have been renamed from being specific to Squid – they were previously $wgUseSquid, $wgSquidServers, $wgSquidServersNoPurge, and $wgSquidMaxage respectively. This aligns them with the related existing variable $wgCdnMaxageLagged. The previous configuration variable names are deprecated, but will be used as the fall back if they are still set. Note that $wgSquidPurgeUseHostHeader has not been renamed, as it is deprecated.
 * (T27707) File type checks for image uploads have been relaxed to allow files containing some HTML markup in metadata. As a result, the $wgAllowTitlesInSVG setting is no longer applied and is now always true. Note that MSIE 7 may still be able to misinterpret certain malformed PNG files as HTML.
 * Introduced $wgVerifyMimeTypeIE to allow disabling the MSIE 6/7 file type detection heuristic on upload, which is more conservative than the checks that were changed above.
 * $wgExternalDiffEngine — Setting this to a string value of 'wikidiff', 'wikidiff2', or 'wikidiff3' will no longer work. This legacy behaviour was deprecated in MediaWiki 1.27, 1.32, and 1.27, respectively.
 * $wgSkipSkin — Setting this instead of $wgSkipSkins, deprecated in 1.23, is now hard-deprecated.
 * $wgLocalInterwiki — Setting this instead of $wgLocalInterwikis, deprecated in 1.23, is now hard-deprecated.
 * $wgProfileOnly — Setting this, deprecated in 1.23, is now hard-deprecated. Instead, set the log file in.
 * $wgProxyList — Setting this to an array with IP addresses in the array keys, which was deprecated in 1.30, no longer works. Instead, $wgProxyList should be an array with IP addresses as the values, or a string path to a file containing one IP address per line.
 * $wgCookieSetOnAutoblock and $wgCookieSetOnIpBlock are now enabled by default.

Removed configuration

 * $wgWikiDiff2MovedParagraphDetectionCutoff — If you still want a custom change size threshold, please specify in php.ini, using the configuration variable wikidiff2.moved_paragraph_detection_cutoff.
 * $wgUseESI - This experimental setting, deprecated in 1.33, is now removed.
 * $wgDebugPrintHttpHeaders - The default of including HTTP headers in the debug log channel is no longer configurable. The debug log itself remains configurable via $wgDebugLogFile.
 * $wgMsgCacheExpiry — The MessageCache uses 24 hours as the expiry for values stored in WANObjectCache. This is no longer configurable.
 * $wgPasswordSalt – This setting, used for migrating exceptionally old, insecure password setups and deprecated since 1.24, is now removed.
 * $wgDBOracleDRCP — If you must use persistent connections, set DBO_PERSISTENT in the 'flags' field for servers in $wgDBServers (or $wgLBFactoryConf).
 * $wgMemCachedDebug — Set the cache "debug" field in $wgObjectCaches instead.
 * $wgActorTableSchemaMigrationStage has been removed. Extension code for MediaWiki 1.31+ finding it unset should treat it as being SCHEMA_COMPAT_NEW.

New user-facing features in 1.34

 * Special:Mute has been added as a quick way for users to block unwanted emails from other users originating from Special:EmailUser.
 * (T207577) Special:NewSection has been created as a shortcut to creating a new section on a page. When linked to, its subpage is used as the target (Special:NewSection/Test redirects to creating a new section in "Test"). Otherwise, it displays a basic interface to allow the end user to specify the target manually.
 * (T220447) Special:Contributions/newbies has been removed for performance and usefulness reasons. Use Special:RecentChanges?userExpLevel=newcomer instead.
 * Special:NewFiles/newbies has been removed for performance and usefulness reasons. Use Special:RecentChanges?userExpLevel=newcomer&namespace=6 instead.

New developer features in 1.34

 * The ImgAuthModifyHeaders hook was added to img_auth.php to allow modification of headers in private wikis.
 * Language::formatTimePeriod now supports the new 'avoidhours' option to output strings like "5 days ago" instead of "5 days 13 hours ago".
 * (T220163) Added SpecialMuteModifyFormFields hook to allow extensions to add fields to Special:Mute.
 * (T100896) Skin authors can define custom OOUI themes using OOUIThemePaths. See https://www.mediawiki.org/wiki/OOUI/Themes for details.
 * (T229035) The GetUserBlock hook was added. Use this instead of GetBlockedStatus.
 * ObjectFactory is available as a service. When used as a service, the object specs can now specify needed DI services.
 * (T222388) Special pages can now be specified as an ObjectFactory spec, allowing the construction of special pages that require services to be injected in their constructor.
 * (T222388) API modules can now be specified as an ObjectFactory spec, allowing the construction of modules that require services to be injected in their constructor.
 * (T117736) The function signature of SpecialContributions::getForm::filters has changed. It now expects definitions of additional filter fields as array rather than string.

Changed external libraries

 * Updated Mustache from 1.0.0 to v3.0.1.
 * Updated OOUI from v0.31.3 to v0.34.0.
 * Updated OOjs from v2.2.2 to v3.0.0.
 * Updated composer/semver from 1.4.2 to 1.5.0.
 * Updated composer/spdx-licenses from 1.4.0 to 1.5.1 (dev-only).
 * Updated mediawiki/codesniffer from 25.0.0 to 26.0.0 (dev-only).
 * Updated cssjanus/cssjanus from 1.2.1 to 1.3.0.
 * Updated wikimedia/at-ease from 1.2.0 to 2.0.0.
 * Updated wikimedia/remex-html from 2.0.1 to 2.1.0.
 * Updated monolog/monolog from 1.22.1 to 1.24.0 (dev-only).
 * Updated wikimedia/object-factory from 1.0.0 to 2.1.0.
 * Updated wikimedia/timestamp from 2.2.0 to 3.0.0.
 * Updated wikimedia/xmp-reader from 0.6.2 to 0.6.3.
 * Updated mediawiki/mediawiki-phan-config from 0.6.0 to 0.6.1 (dev-only).
 * Updated wikimedia/avro from 1.8.0 to 1.9.0 (dev-only).

Removed external libraries

 * The jquery.async module, deprecated in 1.33, was removed.

Bug fixes in 1.34

 * (T222529) If a log entry or page revision is recorded in the database with an empty username, attempting to display it will log an error and return a "no username available" to the user instead of silently displaying nothing or invalid links.

Action API changes in 1.34

 * The 'recenteditcount' response property from action=query list=allusers, deprecated in 1.25, has been removed.
 * (T60993) action=query list=filearchive, list=alldeletedrevisions and prop=deletedrevisions no longer require the 'deletedhistory' user right.
 * In the response to queries that use 'prop=imageinfo', entries for non-existing files (indicated by the 'filemissing' field) now omit the following fields, since they are meaningless in this context: 'timestamp', 'userhidden', 'user', 'userid', 'anon', 'size', 'width', 'height', 'pagecount', 'duration', 'commenthidden', 'parsedcomment', 'comment', 'thumburl', 'thumbwidth', 'thumbheight', 'thumbmime', 'thumberror', 'url', 'sha1', 'metadata', 'extmetadata', 'commonmetadata', 'mime', 'mediadtype', 'bitdepth'. Clients that process these fields should first check if 'filemissing' is set. Fields that are supported even if the file is missing include: 'canonicaltitle', ''archivename' (deleted files only), 'descriptionurl', 'descriptionshorturl'.
 * The 'blockexpiry' result property in list=users and list=allusers will now be returned in the same format used by the rest of the API: ISO 8601 for expiring blocks, and "infinite" for non-expiring blocks.

Action API internal changes in 1.34

 * The exception thrown in ApiModuleManager::getModule has been changed from an MWException to an UnexpectedValueException, thrown by ObjectFactory. ApiModuleManager::getModule now also throws InvalidArgumentExceptions when ObjectFactory is presented with an invalid spec or incorrectly constructed objects.
 * Added ApiQueryBlockInfoTrait.

Languages updated in 1.34
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 Phabricator reports.


 * (T152908) Added language support for N'Ko (nqo).

Breaking changes in 1.34
* CryptRand class * CryptRand service * Functions of the MWCryptRand class: singleton, wasStrong and generate. * SpecialAncientpages => SpecialAncientPages * SpecialConfirmemail => SpecialConfirmEmail * SpecialDeadendpages => SpecialDeadendPages * SpecialFewestrevisions => SpecialFewestRevisions * SpecialListredirects => SpecialListRedirects * SpecialLonelypages => SpecialLonelyPages * SpecialLongpages => SpecialLongPages * SpecialMIMEsearch => SpecialMIMESearch * SpecialMostcategories => SpecialMostCategories * SpecialMostinterwikis => SpecialMostInterwikis * SpecialMostlinked => SpecialMostLinked * SpecialMostlinkedcategories => SpecialMostLinkedCategories * SpecialMostlinkedtemplates => SpecialMostLinkedTemplates * SpecialMostrevisions => SpecialMostRevisions * SpecialNewimages => SpecialNewFiles * SpecialShortpages => SpecialShortPages * SpecialUncategorizedcategories => SpecialUncategorizedCategories * SpecialUncategorizedimages => SpecialUncategorizedImages * SpecialUncategorizedpages => SpecialUncategorizedPages * SpecialUncategorizedtemplates => SpecialUncategorizedTemplates * SpecialUnusedcategories => SpecialUnusedCategories * SpecialUnusedimages => SpecialUnusedImages * SpecialUnusedtemplates => SpecialUnusedTemplates * SpecialUnwatchedpages => SpecialUnwatchedPages * SpecialWantedcategories => SpecialWantedCategories * SpecialWantedtemplates => SpecialWantedTemplates * SpecialWithoutinterwiki => SpecialWithoutInterwiki * Revision::userJoinCond * Revision::pageJoinCond * Revision::selectFields * Revision::selectArchiveFields * Revision::selectTextFields * Revision::selectPageFields * Revision::selectUserFields
 * The global functions wfSuppressWarnings and wfRestoreWarnings, deprecated in 1.26, have been removed. Use Wikimedia\AtEase\AtEase::suppressWarnings and Wikimedia\AtEase\AtEase::restoreWarnings directly.
 * Preferences class, deprecated in 1.31, has been removed.
 * The following parts of code, deprecated in 1.32, were removed in favor of built-in PHP functions:
 * Various Special Page PHP Classes were renamed (mostly casing changes):
 * Language::setCode, deprecated in 1.32, was removed. Use Language::factory to create a new Language object with a different language code.
 * MWNamespace::clearCaches has been removed. So has the $rebuild parameter to MWNamespace::getCanonicalNamespaces, which was deprecated since 1.31.  Instead, reset services, such as by calling $this->overrideMwServices (if your test extends MediaWikiTestCase). Services will generally not pick up configuration changes from after they were created, so you must reset services after any configuration change. Even if your code works now, it is likely to break in future versions as more code is moved to services.
 * The ill-defined "DatabaseOraclePostInit" hook has been removed.
 * PreferencesFormLegacy and PreferencesForm classes, deprecated in 1.32, have been removed.
 * ObjectFactory class, deprecated in 1.31, has been removed.
 * HWLDFWordAccumudlator class, deprecated in 1.28, has been removed.
 * XMPInfo, XMPReader and XMPValidate, deprecated in 1.32, have been removed.
 * The RedirectSpecialPage::execute method could sometimes return a Title object. This behavior was removed, and the method now matches the parent signature (SpecialPage::execute) which is to return HTML string or void.  To obtain the destination title, use RedirectSpecialPage::getRedirect.
 * The 'recenteditcount' response property from action API action=query list=allusers, deprecated in 1.25, has been removed.
 * SearchEngine::userNamespaces, SearchEngine::namespacesAsText, SearchEngine::create, SearchEngine::getSearchTypes and SearchEngine::getNearMatch, methods deprecated in 1.27, have been removed.
 * FileRepo::streamFile, deprecated in 1.26, has been removed.
 * User::randomPassword method, deprecated in 1.27, have been removed.
 * MWNamespace::canTalk, deprecated in 1.30, have been removed.
 * Parser class property $mUniqPrefix, deprecated in 1.26, has been removed.
 * wfArrayFilter and wfArrayFilterByKey, deprecated in 1.32, have been removed.
 * wfMakeUrlIndexes function, deprecated in 1.33, have been removed.
 * Method signatures in WatchedItemQueryServiceExtension have changed from taking User objects to taking UserIdentity objects. Extensions implementing this interface need to be changed accordingly.
 * User::getGroupPage and ::makeGroupLinkHTML, deprecated in 1.29, have been removed. Use UserGroupMembership::getGroupPage and ::getLink instead.
 * User::makeGroupLinkWiki, deprecated in 1.29, has been removed. Use UserGroupMembership::getLink instead.
 * SavepointPostgres, deprecated in 1.31, has been removed.
 * OutputPage::enableSectionEditLinks, OutputPage::sectionEditLinksEnabled, ParserOptions::getEditSection, ParserOptions::setEditSection, and ParserOutput::getEditSectionTokens, ::getTOCEnabled, ::setEditSectionTokens, and ::setTOCEnabled, deprecated in 1.31, have been removed.
 * EditPage::safeUnicodeInput and ::safeUnicodeOutput, deprecated in 1.30, have been removed.
 * Four methods in OutputPage, deprecated in 1.32, have been removed. You should use OutputPage::showFatalError or throw a FatalError instead. The methods are ::showFileCopyError, ::showFileRenameError, ::showFileDeleteError, and ::showFileNotFoundError.
 * ApiBase::truncateArray, deprecated in 1.32, has been removed.
 * IcuCollation::getICUVersion, deprecated in 1.32, has been removed. Use PHP's INTL_ICU_VERSION constant directly.
 * HTMLForm::setSubmitProgressive, deprecated in 1.32, has been removed.
 * ResourceLoaderStartUpModules::getStartupModules and ::getLegacyModules, both deprecated in 1.32, have been removed.
 * BaseTemplate::msgHtml and QuickTemplate::msgHtml, deprecated in 1.32, have been removed. Use ->msg or ->getMsg instead.
 * WatchAction::getUnwatchToken, deprecated in 1.32, has been removed. Instead, use WatchAction::getWatchToken with action 'unwatch' directly.
 * Language::initEncoding, ::recodeForEdit, and recodeInput, deprecated in 1.28, have been removed.
 * PageArchive::getTextFromRow, ::listAllPages, and ::getLastRevisionText, deprecated in 1.32, have been removed.
 * OutputPage::getModuleScripts, ParserOutput::getModuleScripts, deprecated in 1.33, have been removed.
 * User::getPasswordValidity, deprecated in 1.33, has been removed.
 * ApiQueryBase::prepareUrlQuerySearchString, deprecated in 1.33, has been removed.
 * ChangeTags::purgeTagUsageCache, deprecated in 1.33, has been removed.
 * JobQueueGroup::pushLazyJobs, deprecated in 1.33, has been removed.
 * MediaWikiTestCase::stashMwGlobals, deprecated in 1.32, has been removed.
 * SearchEngine::transformSearchTerm, deprecated in 1.32, has been removed.
 * The Block typehint only refers to blocks stored in the database. It should be updated to AbstractBlock in cases where any type of block could be expected.
 * FileRepoStatus, deprecated in 1.25, has been removed.
 * The LegacyHookPreAuthenticationProvider class, deprecated since its creation in 1.27, has been removed.
 * IP::isValidBlock, deprecated in 1.30, has been removed.
 * WikiPage::prepareContentForEdit now doesn't accept an integer for $revision, was deprecated in 1.25.
 * The jquery.byteLength module, deprecated in 1.31, was removed. Use the mediawiki.String module instead.
 * mw.language.specialCharacters, deprecated in 1.33, has been removed. Use require( 'mediawiki.language.specialCharacters' ) instead.
 * The jquery.colorUtil module was removed. Use jquery.color instead.
 * The jquery.checkboxShiftClick module was removed. The functionality is provided by mediawiki.page.ready instead (T232688).
 * The 'jquery.accessKeyLabel' module has been removed. This jQuery plugin now ships as part of the 'mediawiki.util' module bundle.
 * EditPage::submit, deprecated in 1.29, has been removed. Use $this->edit directly.
 * HTMLForm::getErrors, deprecated in 1.28, has been removed. Use getErrorsOrWarnings instead.
 * SpecialPage::getTitle, deprecated in 1.23, has been removed. Use SpecialPage::getPageTitle instead.
 * jquery.ui.effect-bounce, jquery.ui.effect-explode, jquery.ui.effect-fold jquery.ui.effect-pulsate, jquery.ui.effect-slide, jquery.ui.effect-transfer, which are no longer used, have now been removed.
 * SpecialEmailUser::validateTarget, ::getTarget without a sender/user specified, deprecated in 1.30, have been removed.
 * BufferingStatsdDataFactory::getBuffer, deprecated in 1.30, has been removed.
 * The constant DB_SLAVE, deprecated in 1.28, has been removed. Use DB_REPLICA.
 * The constants NS_IMAGE and NS_IMAGE_TALK, deprecated in 1.14, have been removed. Use NS_FILE and NS_FILE_TALK respectively.
 * Replacer, DoubleReplacer, HashtableReplacer and RegexlikeReplacer (deprecated in 1.32) have been removed. Closures should be used instead.
 * OutputPage::addWikiText, ::addWikiTextWithTitle, ::addWikiTextTitleTidy, ::addWikiTextTidy, ::addWikiTextTitle, deprecated in 1.32, have been removed.
 * The $wgUseKeyHeader configuration option and the OutputPage::getKeyHeader method, deprecated in 1.32, have been removed.
 * WebInstallerOutput::addWikiText, deprecated in 1.32, has been removed.
 * Parser::fetchFile, deprecated in 1.32, has been removed. Use the method Parser::fetchFileAndTitle instead.
 * The global function wfBCP47, deprecated in 1.31, has been removed.
 * wfCountDown function, deprecated in 1.31, has been removed. Use \Maintenance::countDown method instead.
 * OutputPage::wrapWikiMsg no longer accepts an options parameter. This was deprecated since 1.20.
 * Skin::outputPage no longer accepts a context. This was deprecated in 1.20.
 * Linker::link no longer accepts a string for the query array, as was deprecated in 1.20.
 * PrefixSearch::titleSearch, deprecated in 1.23, has been removed. Use the SearchEngine::defaultPrefixSearch or ::completionSearch methods instead.
 * The UserRights hook, deprecated in 1.26, has been removed. Instead, use the UserGroupsChanged hook.
 * Skin::getDefaultInstance, deprecated in 1.27, has been removed. Get the instance from MediaWikiServices instead.
 * The UserLoadFromSession hook, deprecated in 1.27, has been removed.
 * The wfResetSessionID global function, deprecated in 1.27, has been removed. Use MediaWiki\Session\SessionManager instead.
 * The wfGetLBFactory global function, deprecated in 1.27, has been removed. Use MediaWikiServices::getInstance->getDBLoadBalancerFactory.
 * The internal method OutputPage->addScriptFile will no longer silently drop calls that use an invalid path (i.e., something other than an absolute path, protocol-relative URL, or full scheme URL), and will instead pass them to the client where they will likely 404. This usage was deprecated in 1.24.
 * Database::reportConnectionError, deprecated in 1.32, has been removed.
 * APIEditBeforeSave hook, deprecated in 1.28, has been removed. Please see EditFilterMergedContent hook for an alternative way to use this feature.
 * API module methods getDescription, getParamDescription, & getExamples, all deprecated in 1.25 and ignored, have been removed.
 * The API module method getDescriptionMessage, deprecated in 1.30, has been removed.
 * The JavaScript global variable wgLoadScript has been removed. Use mw.util.wikiScript( 'load' ) instead.
 * ResourceLoader no longer creates the 'mw.legacy' placeholder object. It has been unused since 1.16 and was deprecated in 1.22. To deprecate a property in JavaScript, use mw.log.deprecate instead.
 * The 'user.groups' module, deprecated in 1.28, was removed. Use the 'user' module instead.
 * The ResourceLoaderContext::expandModuleNames method, deprecated in 1.33, was removed. Use ResourceLoader::expandModuleNames instead.
 * The ability to override User::$mRights has been removed. Use PermissionManager::addTemporaryUserRights instead.
 * Previously, when iterating ResultWrapper with foreach or a similar construct, the range of the index was 1..numRows. This has been fixed to be 0..(numRows-1).
 * The ChangePasswordForm hook, deprecated in 1.27, has been removed. Use the AuthChangeFormFields hook or security levels instead.
 * WikiMap::getWikiIdFromDomain, deprecated in 1.33, has been removed. Use WikiMap::getWikiIdFromDbDomain instead.
 * The config variables $wgHtml5, $wgJsMimeType, and $wgXhtmlDefaultNamespace, which were deprecated and ignored by core since 1.22, are no longer set to any value, and SkinTemplate no longer emits a 'jsmimetype' key. Any extensions not updated since 2013 to cope with this deprecation may now break.
 * (T222637) Passing ResourceLoaderModule objects to ResourceLoader::register or $wgResourceModules is no longer supported. Use the 'class' or 'factory' option of the array format instead.
 * The parameter $lang of the functions generateTOC and tocList in Linker and DummyLinker must be in type Language when present. Other types are deprecated since 1.33.
 * The static properties mw.Api.errors and mw.Api.warnings, deprecated in 1.29, have been removed.
 * ParserOption::getSpeculativeRevIdCallback, deprecated in 1.28, has been removed.
 * The UploadVerification hook, deprecated in 1.28, has been removed. Instead, use the UploadVerifyFile hook.
 * UploadBase:: and UploadFromChunks::stashFileGetKey and stashSession, deprecated in 1.28, have been removed. Instead, please use the getFileKey method on the response from doStashFile.
 * LBFactory::setDomainPrefix and LoadBalancer::setDomainPrefix, deprecated in 1.33, have been removed. Use setLocalDomainPrefix instead.
 * IDatabase::implicitGroupby, deprecated in 1.30, has been removed.
 * IDatabase::doneWrites, deprecated in 1.31, has been removed. Use IDatabase::lastDoneWrites instead.
 * Database::reportConnectionError, deprecated in 1.32, has been removed.
 * LoadBalancer::laggedSlaveUsed, deprecated in 1.28, has been removed. Use LoadBalancer::laggedReplicaUsed instead.
 * Database::getProperty, deprecated in 1.28, has been removed.
 * IDatabase::getWikiId, deprecated in 1.30, has been removed. Use IDatabase::getDomainID instead.
 * (T191231) Support for using Oracle or MSSQL as database backends has been dropped.
 * MessageCache::destroyInstance has been removed. Instead, call MediaWikiTestCase::resetServices.
 * SearchResult protected field $searchEngine is removed and no longer initialized after calling SearchResult::initFromTitle.
 * The UserIsBlockedFrom hook is only called if a block is found first, and should only be used to unblock a blocked user.
 * Parameters for index.php from PATH_INFO, such as the title, are no longer written to $_GET.
 * The selectFields methods on classes LocalFile, ArchivedFile, OldLocalFile, DatabaseBlock, and RecentChange, deprecated in 1.31, have been removed. Use the corresponding getQueryInfo methods instead.
 * The following methods on Revision, deprecated since 1.31, have been removed. Use RevisionStore::getQueryInfo or RevisionStore::getArchiveQueryInfo instead.
 * User::setNewpassword, deprecated in 1.27 has been removed.
 * The ObjectCache::getMainWANInstance and ObjectCache::getMainStashInstance functions, deprecated since 1.28, have been removed.
 * Language::$dataCache has been removed (without prior deprecation, for practical reasons). Use MediaWikiServices instead to get a LocalisationCache.

Deprecations in 1.34
$wgGroupPermissions['sysop']['blockemail'] = true;
 * The MWNamespace class is deprecated. Use NamespaceInfo.
 * ExtensionRegistry->load is deprecated, as it breaks dependency checking. Instead, use ->queue.
 * User::isBlocked is deprecated since it does not tell you if the user is blocked from editing a particular page. Use User::getBlock or PermissionManager::isBlockedFrom or PermissionManager::userCan instead.
 * User::isLocallyBlockedProxy and User::inDnsBlacklist are deprecated and moved to the BlockManager as private helper methods.
 * User::isDnsBlacklisted is deprecated. Use BlockManager::isDnsBlacklisted instead.
 * The Config argument to ChangesListSpecialPage::checkStructuredFilterUiEnabled is deprecated. Pass only the User argument.
 * WatchedItem::getUser is deprecated. Use getUserIdentity.
 * Passing a Title as the first parameter to the getTimestampById method of RevisionStore is deprecated. Omit it, passing only the remaining parameters.
 * Title::getPreviousRevisionId and Title::getNextRevisionId are deprecated. Use RevisionLookup::getPreviousRevision and RevisionLookup::getNextRevision.
 * The Title parameter to RevisionLookup::getPreviousRevision and RevisionLookup::getNextRevision is deprecated and should be omitted.
 * MWHttpRequest::factory is deprecated. Use HttpRequestFactory.
 * The Http class is deprecated. For the request, get, and post methods, use HttpRequestFactory. For isValidURI, use MWHttpRequest::isValidURI. For getProxy, use (string)$wgHTTPProxy. For createMultiClient, construct a MultiHttpClient directly.
 * Http::$httpEngine is deprecated and has no replacement. The default 'guzzle' engine will eventually be made the only engine for HTTP requests.
 * RepoGroup::singleton, RepoGroup::destroySingleton, RepoGroup::setSingleton, wfFindFile, and wfLocalFile are all deprecated. Use MediaWikiServices instead.
 * The getSubjectPage, getTalkPage, and getOtherPage of Title are deprecated. Use NamespaceInfo's getSubjectPage, getTalkPage, and getAssociatedPage.
 * MWMessagePack class, no longer used, has been deprecated in 1.34.
 * The Block class is separated into DatabaseBlock (for blocks stored in the database), and SystemBlock (for temporary blocks created by the system). SystemBlock should be used when creating any temporary blocks. Block is a deprecated alias for DatabaseBlock.
 * Parser::$mConf is deprecated. It will be removed entirely in a later version. Some context can be found at T224165.
 * Constructing Parser directly is deprecated. Obtain one from ParserFactory.
 * Title::moveSubpages is deprecated. Use MovePage::moveSubpages or MovePage::moveSubpagesIfAllowed.
 * The MWNamespace class is deprecated. Use MediaWikiServices::getNamespaceInfo.
 * (T62260) Hard deprecate Language::getExtraUserToggles method.
 * Language::viewPrevNext function is deprecated, use PrevNextNavigationRenderer::buildPrevNextNavigation instead
 * User::trackBlockWithCookie and DatabaseBlock::clearCookie are deprecated. Use BlockManager::trackBlockWithCookie and BlockManager::clearCookie instead.
 * DatabaseBlock::setCookie, DatabaseBlock::getCookieValue, DatabaseBlock::getIdFromCookieValue and AbstractBlock::shouldTrackWithCookie are moved to internal helper methods for BlockManager::trackBlockWithCookie.
 * ResourceLoaderContext::getConfig and ResourceLoaderContext::getLogger have been deprecated. Inside ResourceLoaderModule subclasses, use the local methods instead. Elsewhere, use the methods from the ResourceLoader class.
 * The Profiler::setTemplated and Profiler::getTemplated methods have been deprecated. Use Profiler::setAllowOutput and Profiler::getAllowOutput instead.
 * The Preprocessor_DOM implementation has been deprecated. It will be removed in a future release.  Use the Preprocessor_Hash implementation instead.
 * Sanitizer::attributeWhitelist and Sanitizer::setupAttributeWhitelist have been deprecated; they will be made private in the future.
 * SearchResult::termMatches method is deprecated. It was unreliable because only populated by few search engine implementations. Use SqlSearchResult::getTermMatches if really needed.
 * SearchResult::getTextSnippet( $terms ) the $terms param is being deprecated and should no longer be passed. Search engine implemenations should be responsible for carrying relevant information needed for highlighting with their own SearchResultSet/SearchResult sub-classes.
 * SearchResultSet::free method is deprecated.
 * SearchEngine::$searchTerms protected field is deprecated. Moved to SearchDatabase.
 * The use of the $terms param in the ShowSearchHit and ShowSearchHitTitle hooks is highly discouraged as it's only populated by SearchDatabase search engines.
 * Skin::escapeSearchLink is deprecated. Use Skin::getSearchLink or the skin template option 'searchaction' instead.
 * Skin::getRevisionId and Skin::isRevisionCurrent have been deprecated. Use OutputPage::getRevisionId and OutputPage::isRevisionCurrent instead.
 * LoadBalancer::haveIndex and LoadBalancer::isNonZeroLoad have been deprecated.
 * FileBackend::getWikiId has been deprecated. Use FileBackend::getDomainId instead.
 * User::getRights and User::$mRights have been deprecated. Use PermissionManager::getUserPermissions instead.
 * The LocalisationCacheRecache hook no longer allows purging of message blobs to be prevented. Modifying the $purgeBlobs parameter now has no effect.
 * SVGMetadataExtractor::getMetadata has been deprecated. Instead, you should use SVGReader->getMetadata directly.
 * The following public properties on AbstractBlock are deprecated: $mReason, $mTimestamp, $mExpiry, $mHideName. Use the getters/setters instead.
 * The following public properties on DatabaseBlock are deprecated: $mAuto, $mParentBlockId. To check for an autoblock use DatabaseBlock::getType; to check for the parent ID, use DatabaseBlock::getParentBlockId.
 * SearchEngine::userHighlightPrefs is deprecated, simply stop passing $contextlines and $contextchars to the SearchHighlighter methods, they will use proper defaults defined in SearchHighlighter::DEFAULT_CONTEXT_LINES and DEFAULT_CONTEXT_CHARS.
 * SearchUpdate constructor: passing a string as the title param and or a boolean or a string as the content will produce a deprecation warning.
 * SearchEngine::getTextFromContent is deprecated, use getTextForSearchIndex directly from the Content object.
 * SearchEngine::textAlreadyUpdatedForIndex is deprecated, given the deprecation above this method is no longer needed/called and should not be implemented by SearchEngine implementation.
 * IDatabase::bufferResults has been deprecated. Use query batching instead.
 * MessageCache::singleton is deprecated. Use MediaWikiServices::getMessageCache.
 * ObjectCache::getWANInstance is deprecated. Use MediaWikiServices::getMainWANObjectCache instead.
 * ObjectCache::newWANCacheFromParams is deprecated. Use MediaWikiServices::getMainWANObjectCache instead.
 * Constructing MovePage directly is deprecated. Use MovePageFactory.
 * TempFSFile::factory has been deprecated. Use TempFSFileFactory instead.
 * wfIsBadImage is deprecated. Use the BadFileLookup service instead.
 * Building a new SearchResult is hard-deprecated, always call SearchResult::newFromTitle. This class is being refactored into an abstract class. If you extend this class please be sure to override all its methods or extend RevisionSearchResult.
 * Skin::getSkinNameMessages is deprecated and no longer used.
 * The mediawiki.RegExp module is deprecated; use mw.util.escapeRegExp instead.
 * Specifying a SpecialPage object for the list of special pages (either through the SpecialPage_initList hook or by adding to $wgSpecialPages) is now deprecated.
 * WebInstaller::getInfoBox, getWarningBox and getErrorBox are deprecated. Use Html::errorBox or Html::warningBox instead.
 * Use of ActorMigration with 'ar_user', 'img_user', 'oi_user', 'fa_user', 'rc_user', 'log_user', and 'ipb_by' is deprecated. Queries should be adjusted to use the corresponding actor fields directly. Note that use with 'rev_user' is *not* deprecated at this time.
 * Specifying both the class and factory parameters for ApiModuleManager::addModule is now deprecated. The ObjectFactory spec should be used instead.
 * The UserIsHidden hook is deprecated. Use GetUserBlock instead, and add a system block that hides the user.
 * The GetBlockedStatus hook is deprecated. Use GetUserBlock instead, to add or remove a block.
 * $wgContentHandlerUseDB is deprecated and should always be true.
 * StreamFile::send404Message and StreamFile::parseRange are now deprecated. Use HTTPFileStreamer::send404Message and HTTPFileStreamer::parseRange respectively instead.
 * Global variable $wgSysopEmailBans is deprecated; to allow sysops to ban users from sending emails, use
 * ApiQueryBase::showHiddenUsersAddBlockInfo is deprecated. Use ApiQueryBlockInfoTrait instead.
 * PasswordReset is now a service, its direct instantiation is deprecated.
 * RESTBagOStuff users should specify either "JSON" or "PHP" serialization type.
 * The global function wfIsHHVM is deprecated and will now always return false regardless of the runtime environment. This is part of the continuing work to remove HHVM support from MediaWiki, which started in MediaWiki 1.31.
 * Language::getLocalisationCache is deprecated. Use MediaWikiServices instead.
 * The following Language methods are deprecated: isSupportedLanguage, isValidCode, isValidBuiltInCode, isKnownLanguageTag, fetchLanguageNames, fetchLanguageName, getFileName, getMessagesFileName, getJsonMessagesFileName. Use the new LanguageNameUtils class instead. (Note that fetchLanguageName(s) are called getLanguageName(s) in the new class.)

Other changes in 1.34

 * Added option to specify "Various authors" as author in extension credits using "..." as the only author name. If the "author" array contains more than one entry and "..." is one of the entries in the array, "..." will be parsed as "others" (version-poweredby-others i18n message) like previously.

Compatibility
MediaWiki 1.34 requires PHP 7.2.9 or later, and the following PHP extensions:


 * ctype
 * dom
 * fileinfo
 * iconv
 * json
 * mbstring
 * xml

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

The supported versions are:


 * MySQL 5.5.8 or later
 * PostgreSQL 9.2 or later
 * SQLite 3.8.0 or later

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/Special:MyLanguage/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.