MediaWiki 1.33

MediaWiki 1.33 is the latest release of MediaWiki. Consult the file for the full list of changes. It was deployed on Wikimedia Foundation wikis through incremental "wmf" alpha branches from 23 October 2018 until 10 April 2019. The 1.33.0 stable release was released on 2 July 2019. Download the latest releases or checkout the  branch in Git to follow this release.

Known issues

 * MediaWiki enforces $wgDBprefix to end with the "_" character if set, causing this error otherwise: InvalidArgumentException: A non-empty prefix must end with "_".

Upgrading notes for 1.33
1.33 has several database changes since 1.32, 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 1.33 upgrades are below:


 * Some external link searches will not work correctly until update.php (or refreshExternallinksIndex.php) is run. These include searches for links using IP addresses, internationalized domain names, and possibly mailto links.
 * If you ran migrateActors.php using an older version of MediaWiki and want to run your wiki with $wgActorTableSchemaMigrationStage SCHEMA_COMPAT_READ_OLD, note that log_search rows needed to find revision deletions by target user were incorrectly deleted. See T215464 for details.
 * If revision deletions were performed when the wiki was configured with $wgActorTableSchemaMigrationStage SCHEMA_COMPAT_WRITE_BOTH and without migrateActors.php having been run, the log_search table may contain rows with empty values for "target_author_actor" which will prevent log searches for revision deletions by target user from finding those log entries. These rows may be corrected by (re-)running migrateActors.php.

For notes on 1.32.x and older releases, see HISTORY.

Changes since MediaWiki 1.33.0-rc.0

 * (T225558) Update installer link to PHP intl.
 * (T225901) Only attempt to deduplicate if there is data in archive and revision tables.
 * (T225564) Fetch tag ID before calling undefineTag.
 * (T225496) Detect APC for MainCacheType in CLI installer.
 * Call unpack with correct parameters in MimeAnalyzer.php for PHP 7.0 support.
 * (T212613) Style change tags correctly on Special:Newpages.
 * (T202211) Fix SQLite patch-(page|template)links-fix-pk.sql column order.

New configuration

 * $wgEnablePartialBlocks – This enables the Partial Blocks feature, which gives accounts with block permissions the ability to block users, IPs, and IP ranges from editing specific pages, while allowing them to edit the rest of the wiki. It is a temporary setting for gradual enablement, current default to `false`, and will be set to `true` and then removed once initial development completes.

Changed configuration

 * $wgChangeTagsSchemaMigrationStage (T193868) — This temporary setting, added in MediaWiki 1.32, now defaults to MIGRATION_NEW instead of MIGRATION_WRITE_BOTH.
 * $wgPasswordPolicy – There is a new password policy to check that the account's password is not in the large blacklist. This is enabled by default for the built-in user groups bureaucrat, sysop, interface-admin, and bot. To configure this for other user groups, set the `PasswordNotInLargeBlacklist` flag `true`.
 * $wgPasswordDefault – There is a new password type configuration using Argon2 password hashing (which requires PHP 7.2 and above). It's designed to resist timing attacks, and (on systems with PHP 7.3+) GPU hacking; if you configure argon2 to be used, by default, it will automatically choose the best available algorithm depending on which version of PHP you have available. To use this, you can set `$wgPasswordDefault = 'argon2';`.
 * $wgActorTableSchemaMigrationStage now defaults to reading the new schema. update.php will back-populate the new database fields due to the changed setting, which may take some time on large wikis. You can avoid downtime by following a process like that described in T188327.

Removed configuration

 * $wgTagStatisticsNewTable (T199334) — This temporary setting, added in MediaWiki 1.32, has now been removed. When loading Special:Tags, MediaWiki will now always use the `change_tag_def` instead of the `change_tag` table. $wgUseTidy, $wgTidyBin, $wgTidyConf, $wgTidyOpts, $wgTidyInternal, and $wgDebugTidy – These options, all deprecated since 1.26, have now all been removed, as MediaWiki now always tidies user output. The $wgTidyConfig setting remains only for experimental features and debugging, and should not be used.
 * $wgEnableParserCache – This setting has been deprecated since 1.26, has now been removed. If you still desire to disable the parser cache, instead you can set `$wgParserCacheType = CACHE_NONE;`.
 * $wgCommentTableSchemaMigrationStage – This temporary migration setting has now been removed. Code finding it unset should treat it as being MIGRATION_NEW.
 * $wgAuth – This old setting, deprecated in 1.27, has been removed as part of the removal of AuthPlugin.
 * $wgSitesCacheFile – This configuration was introduced in 1.25 with the intent to allow sites to configure a file in which to cache the SiteStore database table, but it was never used. SiteStore already caches its information by default using BagOStuff (e.g. Memcached or APC).
 * $wgClockSkewFudge – This setting was used by User.php to let sites adjust by how much MediaWiki would fudge when trying to minimize the chances of a user.user_touched database update to the "current" timestamp being before the value already there (e.g. due to clock skew between different servers). This is no longer a problem, because the code now ensures the timestamp is always higher than the previous one. The writes are guarded with CAS logic (check and set), which prevents updates that would overlap.
 * $wgDBmysql5 (T196185) - This experimental setting, deprecated in 1.31, has been removed.

New user-facing features in 1.33

 * (T96041) __EXPECTUNUSEDCATEGORY__ on a category page causes the category to be hidden on Special:UnusedCategories.
 * (T210814) SVGs are now by default displayed in wiki language on image pages.
 * Special:CreateAccount now warns the user if their chosen username has to be normalized.
 * (T205040) Multilingual images are now be displayed in the current parse language where available.
 * Special:ActiveUsers will no longer filter out users who became inactive since the last time the active users query cache was updated.
 * (T215675) RecentChange and ManualLogEntry implement new Taggable interface.
 * (T215675) Added a hook, ManualLogEntryBeforePublish, to allow extensions to modify (example: add tags) log entries.

New developer features in 1.33

 * The AuthManagerLoginAuthenticateAudit hook has a new parameter for additional information about the authentication event.
 * TextContent::getText was introduced as a replacement for Content::getNativeData for text-based content models.
 * (T214706) LinksUpdate::getAddedExternalLinks and LinksUpdate::getRemovedExternalLinks were introduced.
 * (T213893) Added 'MaintenanceUpdateAddParams' hook
 * (T219655) The MarkPatrolled hook has a new parameter for the tags associated with this entry in the patrol log.
 * (T212472) Extensions can now specify platform abilities they require to work, limited to shell access for now.

New external libraries

 * Added wikimedia/password-blacklist 0.1.4.
 * Added guzzlehttp/guzzle 6.3.3.

Changed external libraries

 * Updated OOUI from v0.29.2 to v0.31.3.
 * Updated OOjs Router from pre-release to v0.2.0.
 * Updated moment from v2.19.3 to v2.24.0.
 * Updated wikimedia/xmp-reader from 0.6.0 to 0.6.2.
 * Updated wikimedia/scoped-callback from 2.0.0 to 3.0.0.
 * Updated jquery-client from 2.0.1 to 2.0.2.
 * Updated pear/net_smtp from 1.8.0 to 1.8.1.
 * Updated cssjanus/cssjanus from 1.2.0 to 1.3.0.
 * Updated wikimedia/php-session-serializer from 1.0.6 to 1.0.7.

Removed external libraries

 * (T219403) jquery.ui.spinner, deprecated since 1.31, was removed.

New developer libraries

 * Added jakub-onderka/php-console-highlighter 0.3.2 explicitly (dev-only).
 * Added mediawiki/mediawiki-phan-config 0.5.0 (dev-only).

Changed developer libraries

 * Updated wikimedia/ip-set from 1.3.0 to 2.0.1.
 * The deprecated IPSet\IPSet alias was removed, Wikimedia\IPSet must be used instead.
 * Updated psy/psysh from 0.9.6 to 0.9.9 (dev-only).
 * Updated nikic/php-parser from 3.1.3 to 3.1.5 (dev-only).
 * Updated mediawiki/mediawiki-codesniffer from 22.0.0 to 25.0.0 (dev-only).
 * Updated qunitjs from 2.6.2 to 2.9.1.

Removed developer libraries

 * The jetbrains/phpstorm-stubs repository was removed in favour of the minimal stubs we need, which are kept in the new `.phan/internal_stubs` directory (dev-only).

Bug fixes in 1.33

 * (T164211) Special:UserRights could sometimes fail with a "conflict detected" error when there weren't any conflicts.
 * (T216029) Chrome redirects to Special:BadTitle after editing a section with a non-Latin name on a page with non-Latin characters in title.
 * (T222385) resourceloader: Use AND instead of OR for upsert conds in saveFileDependencies.

Action API changes in 1.33

 * (T198913) Added 'ApiOptions' hook.
 * The JSON formatversion=2 is no longer experimental.
 * Internal API errors (those with code beginning "internal_api_error") will include the exception class name in a data field named "errorclass".
 * Class names are not guaranteed to remain stable, and in particular database exceptions will now include the "Wikimedia\Rdbms\" prefix in the class name.
 * The code including an exception class name is deprecated. In the future, all internal errors will use code "internal_api_error".
 * (T212356) When using action=delete on pages with many revisions, the module may return a boolean-true 'scheduled' and no 'logid'. This signifies that the deletion will be processed via the job queue.
 * action=setnotificationtimestamp will now update the watchlist asynchronously if entirewatchlist is set, so updates may not be visible immediately
 * Block info will be added to "blocked" errors from more modules.
 * (T216245) Autoblocks will now be spread by action=edit and action=move.
 * action=query&meta=userinfo has a new uiprop, 'latestcontrib', that returns the date of user's latest contribution.
 * (T25227) action=logout now requires to be posted and have a csrf token.

Action API internal changes in 1.33

 * A number of deprecated methods for API documentation, intended for overriding by extensions, are no longer called by MediaWiki, and will emit deprecation notices if your extension attempts to use them:
 * ApiBase::getDescription (deprecated in 1.25)
 * ApiBase::getParamDescription (deprecated in 1.25)
 * ApiBase::getExamples (deprecated in 1.25)
 * ApiBase::getDescriptionMessage (deprecated in 1.30)
 * Additionally, the 'APIGetDescription' and 'APIGetParamDescription' hooks have been removed, as their only use was to let extensions override values returned by getDescription and getParamDescription, respectively.
 * API error codes may only contain ASCII letters, numbers, underscore, and hyphen. Methods such as ApiBase::dieWithError and ApiMessageTrait::setApiCode will throw an InvalidArgumentException if passed a bad code.
 * ApiBase::checkTitleUserPermissions now takes an options array as its third parameter. Passing a User object or null is deprecated.
 * The api-feature-usage log channel now has log context. The text message is deprecated and will be removed in the future.

Languages updated in 1.33
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.


 * (T203908) Added language support for Eastern Pwo (kjp).
 * (T213717) Fixed a translation error on Goan Konkani (gom-deva) translations for NS_TEMPLATE.
 * (T212221) Added $digitTransformTable for Santali (sat).
 * (T216479) Added language support for Saisiyat (xsy).
 * (T219728) Added support for new Japanese era name "Reiwa"

Breaking changes in 1.33

 * The parameteter $lang in DifferenceEngine::setTextLanguage must be of type Language. Other types are deprecated since 1.32.
 * Skin::doEditSectionLink requires type Language for the parameter $lang. The parameters $tooltip and $lang are mandatory. Omitting the parameters is deprecated since 1.32.
 * Language::truncate, deprecated in 1.31, has been removed.
 * UtfNormal, deprecated in 1.25, was removed. Use UtfNormal\Validator directly instead.
 * (T197179) In OOUI HTMLForm fields, the parameters 'notice', 'notice-messages', and 'notice-message', which were deprecated in 1.32, were removed. Instead, use 'help', 'help-message', and 'help-messages'.
 * (T197179) HTMLFormField::getNotices, deprecated in 1.32, was removed.
 * The "Parsoid v1" compatibility mappings in ParsoidVirtualRESTService and RestbaseVirtualRESTService, deprecated since 1.26, have been removed. Use the RESTBase v1 or Parsoid v3 API instead.
 * ParserOptions defaults 'tidy' to true now, since the untidy modes of the parser are being deprecated and ParserOptions::getCanonicalOverrides has always been true at any rate.
 * Support for disabling tidy and external tidy implementations has been removed. This was deprecated in 1.32. The pure PHP Remex tidy implementation is now used and no configuration is necessary.
 * A number of deprecated methods for API documentation, intended for overriding by extensions, are no longer called by MediaWiki, and will emit deprecation notices if your extension attempts to use them:
 * ApiBase::getDescription (deprecated in 1.25)
 * ApiBase::getParamDescription (deprecated in 1.25)
 * ApiBase::getExamples (deprecated in 1.25)
 * ApiBase::getDescriptionMessage (deprecated in 1.30)
 * Additionally, the 'APIGetDescription' and 'APIGetParamDescription' hooks have been removed, as their only use was to let extensions override values returned by getDescription and getParamDescription, respectively.
 * The authentication hooks 'AbortAutoAccount' 'AbortNewAccount', 'AbortLogin', 'LoginUserMigrated', 'UserCreateForm', and 'UserLoginForm', all deprecated by the creation of AuthManager in 1.27, have been removed. This also means that the FakeAuthTemplate and LoginForm classes are removed, that FakeAuthTemplate is no longer passed into LoginSignupSpecialPage->getFieldDefinitions, and that LoginSignupSpecialPage->getBCFieldDefinitions is removed.
 * The 'jquery.localize' module, deprecated in 1.32, has been removed. Instead, use 'jquery.i18n'.
 * The hooks LanguageGetSpecialPageAliases and LanguageGetMagic, deprecated since 1.16, have now been removed. Instead, use $specialPageAliases or $magicWords respectively in a $wgExtensionMessagesFiles file.
 * The following methods of the Preferences class, deprecated in 1.31, have been removed:
 * getSaveBlacklist
 * loadPreferenceValues
 * getOptionFromUser
 * profilePreferences
 * skinPreferences
 * filesPreferences
 * datetimePreferences
 * renderingPreferences
 * editingPreferences
 * rcPreferences
 * watchlistPreferences
 * searchPreferences
 * miscPreferences
 * generateSkinOptions
 * getDateOptions
 * getImageSizes
 * getThumbSizes
 * validateSignature
 * cleanSignature
 * getTimezoneOptions
 * filterIntval
 * filterTimezoneInput
 * getTimeZoneList
 * mw.util.jsMessage, deprecated in 1.20, was removed. Use mw.notify instead.
 * (T61113) User::EDIT_TOKEN_SUFFIX was removed. It was deprecated since 1.27.
 * The 'mediawiki.api' module aliases, deprecated in 1.32, have been removed. Specifically: mediawiki.api.category, mediawiki.api.edit, mediawiki.api.login, mediawiki.api.options, mediawiki.api.parse, mediawiki.api.upload, mediawiki.api.user, mediawiki.api.watch, mediawiki.api.messages, and mediawiki.api.rollback.
 * The 'jquery.byteLimit' module alias for 'jquery.lengthLimit', deprecated in 1.31, was removed.
 * Revision::fetchRevision, deprecated in 1.28, was removed.
 * Class SquidUpdate, deprecated in 1.27, was removed.
 * Title->getSquidURLs, deprecated in 1.27, was removed. Instead, use Title->getCdnUrls.
 * Title::escapeFragmentForURL, deprecated in 1.30, was removed. Use Sanitizer::escapeIdForLink or escapeIdForExternalInterwiki instead.
 * Title->canTalk, deprecated in 1.30, was removed. Instead, use Title->canHaveTalkPage.
 * Title's methods for site and user page related to CSS and JS, deprecated in 1.31, were removed:
 * Title->isCssOrJsPage — Use Title->isSiteConfigPage
 * Title->isCssJsSubpage – Use Title->isUserConfigPage
 * Title->getSkinFromCssJsSubpage – Use Title->getSkinFromConfigSubpage
 * Title->isCssSubpage – Use Title->isUserCssConfigPage
 * Title->isJsSubpage – Use Title->isUserJsConfigPage
 * SiteSQLStore, deprecated in 1.27 and whose only method, ::newInstance, would return the global SiteStore instance, has been removed. You can get to this via MediaWiki\MediaWikiServices::getInstance->getSiteStore directly.
 * Linker::formatSize, deprecated in 1.28, has been removed (with DummyLinker's). Instead, use Language->formatSize with the relevant Language object.
 * Linker::formatTemplates, deprecated in 1.28, has been removed (along with the version in DummyLinker). You can use TemplatesOnThisPageFormatter directly.
 * EventRelayerGroup::singleton, deprecated in 1.27, has been removed. You can use MediaWikiServices::getInstance->getEventRelayerGroup directly.
 * LinkCache->addLink, deprecated in 1.27, has been removed. It is thought to be unused, and is distinct from OutputPage->addLink, which remains.
 * JsonContent->getJsonData, deprecated in 1.25, has been removed. Instead, use JsonContent->getData.
 * MWExceptionHandler::getLogId, deprecated in 1.27, has been removed, as the exception ID is the same as the request ID, from WebRequest::getRequestId.
 * SearchEngine::getNearMatchResultSet, deprecated in 1.27, has been removed. You can use SearchEngine::getNearMatcher instead.
 * EmailNotification::updateWatchlistTimestamp, deprecated in 1.27, has been removed. Instead, use WatchedItemStore::updateNotificationTimestamp directly.
 * User::getGroupName and ::getGroupMember, both deprecated in 1.29, have been removed. Instead, please use UserGroupMembership::getGroupName and UserGroupMembership::getGroupMemberName.
 * Backwards compatibility for setting wgSessionsInObjectCache to false or using wgSessionHandler, both of which were deprecated in 1.27 with the introduction of SessionManager, has been removed.
 * SessionManager::autoCreateUser, deprecated in 1.27, has been removed. Use MediaWiki\Auth\AuthManager::autoCreateUser instead.
 * The mw.libs.jpegmeta property, deprecated in 1.31, was removed. Use require( 'mediawiki.libs.jpegmeta' ) instead.
 * The mw.user.stickyRandomId method, deprecated in 1.32, was removed. Use mw.user.getPageviewToken instead.
 * Removed deprecated class property WikiRevision::$importer.
 * ResourceLoaderFileModule::readStyleFiles now requires its $context parameter.
 * The ChangeList::insertArticleLink method, that was deprecated in 1.27, has been removed.
 * MessageBlobStore::__construct now requires its $rl parameter.
 * Second parameter to Sanitizer::escapeIdReferenceList (deprecated in 1.31) has been removed.
 * The 'jquery.xmldom' module has been removed.
 * The 'jquery.mockjax' module has been removed.
 * The 'jquery.hidpi' module, deprecated in 1.32, has been removed.
 * AuthPlugin and related code, deprecated in 1.27, has been removed. Extensions should instead use AuthManager. The following no longer exist:
 * The AuthPlugin class itself and the related AuthPluginUser class and i18n
 * The AuthPluginSetup and AuthPluginAutoCreate hooks
 * The transitional wrapper classes AuthPluginPrimaryAuthenticationProvider, AuthManagerAuthPlugin, and AuthManagerAuthPluginUser.
 * The $wgAuth configuration setting and its use in Setup.php and unit tests
 * (T217772) The 'wgAvailableSkins' mw.config key in JavaScript, was removed.
 * Language::markNoConversion, deprecated in 1.32, has been removed. Use LanguageConverter::markNoConversion instead.
 * BagOStuff::modifySimpleRelayEvent method has been removed.
 * ParserOutput::getLegacyOptions, deprecated in 1.30, has been removed. Use ParserOutput::allCacheVaryingOptions instead.
 * CdnCacheUpdate::newSimplePurge, deprecated in 1.27, has been removed. Use CdnCacheUpdate::newFromTitles instead.
 * Handling of multiple arguments by the Block constructor, deprecated in 1.26, has been removed.
 * The translation of main page in Sardinian (sc) was changed from "Pàgina Base" to "Pàgina printzipale". Existing wikis using this content language need to move the main page or change the name through MediaWiki:Mainpage page.
 * wfSplitWikiID, deprecated in 1.32, has been removed.
 * MessageBlobStore::getBlob, deprecated in 1.27, has been removed. Use ::getBlobs instead.
 * The .background-size LESS mixin, deprecated in 1.27, has been removed.
 * ReadOnlyMode::clearCache and ConfiguredReadOnlyMode::clearCache have been removed. Use MediaWikiTestCase::overrideMwServices instead.

Deprecations in 1.33

 * The configuration option $wgUseESI has been deprecated, and is expected to be removed in a future release.
 * The configuration option $wgSquidPurgeUseHostHeader has been deprecated, and is expected to be removed in a future release.
 * The configuration options $wgFixArabicUnicode and $wgFixMalayalamUnicode, introduced in MW 1.17, have been deprecated. These fixes will always be applied for Arabic and Malayalam in the future.  Please enable these on your local wiki (if you have them explicitly set to false) and run maintenance/cleanupTitles.php to fix any existing page titles.
 * The LegacyHookPreAuthenticationProvider class, deprecated since its creation in 1.27 as part of the AuthManager re-write, now emits deprecation warnings. This will help identify the issue if you added it to $wgAuthManagerConfig.
 * wfSplitWikiId is now deprecated. Cache key generation should have the wiki domain ID as a key component and use makeGlobalKey.
 * (T202094) Title::getUserCaseDBKey is deprecated; instead, please use Title::getDBKey, which doesn't vary case.
 * User::getPasswordValidity is now deprecated. User::checkPasswordValidity returns the same information in a more useful format.
 * For Linker::generateTOC and Linker::tocList, passing strings or booleans as the $lang parameter was deprecated. The same applies to DummyLinker.
 * The PasswordPolicy 'PasswordCannotBePopular' has been deprecated. To follow best practices, it is reccommended to use 'PasswordNotInLargeBlacklist' instead which blacklists 100,000 commonly used passwords.
 * (T208862) Action::requiresUnblock is now called from Title::getUserPermissionsErrors and Title::userCan. Previously, the method was only called in Action::checkCanExecute. Actions should ensure that their requiresUnblock returns the proper result (the default is `true`).
 * (T211608) The MediaWiki\Services namespace has been renamed to Wikimedia\Services. The old name is still supported, but deprecated.
 * (T155582) Content::getNativeData has been deprecated. Please use model-specific getters, such as TextContent::getText.
 * The class WebInstallerOutput is now marked as @private.
 * (T209699) The jquery.async module has been deprecated. JavaScript code that needs asynchronous behaviour should use Promises.
 * Password::equals is deprecated, use verify.
 * BaseTemplate::msgWiki and QuickTemplate::msgWiki will be removed. Use other means to fetch a properly escaped message string or Message object.
 * (T126091) The 'ResourceLoaderTestModules' hook, which lets you declare QUnit testing code for your JavaScript modules, is deprecated. Instead, you can now use the new extension registration key 'QUnitTestModule'.
 * (T213426) The jquery.throttle-debounce module has been deprecated. JavaScript code that needs this behaviour should use OO.ui.debounce/throttle.
 * The mw.language.specialCharacters property from the 'mediawiki.language.specialCharacters' module has been deprecated. Use require( 'mediawiki.language.specialCharacters' ) instead.
 * ChangeTags::purgeTagUsageCache has been deprecated, and is expected to be removed in a future release.
 * Passing a User object or null as the third parameter to ApiBase::checkTitleUserPermissions has been deprecated. Pass an array [ 'user' => $user ] instead.
 * (T211578) Block::prevents is deprecated. Use Block::isEmailBlocked, Block::isCreateAccountBlocked and Block::isUsertalkEditAllowed to get and set block properties; use Block::appliesToRight and Block::appliesToUsertalk to check block behaviour.
 * The api-feature-usage log channel now has log context. The text message is deprecated and will be removed in the future.
 * The FileBasedSiteLookup class has been deprecated. For a cacheable SiteLookup implementation, use CachingSiteStore instead.
 * Language::viewPrevNext function is deprecated, use SpecialPage::buildPrevNextNavigation instead
 * ManualLogEntry::setTags is deprecated, use ManualLogEntry::addTags instead. The setTags method was overriding the tags, addTags doesn't override, only adds new tags.
 * Block::isValid is deprecated, since it is no longer needed in core.
 * Calling Maintenance::hasArg as well as Maintenance::getArg with no parameter has been deprecated. Please pass the argument number 0.
 * ResourceLoaderContext::expandModuleNames has been deprecated. Use ResourceLoader::expandModuleNames instead.

Other changes in 1.33

 * (T201747) Html::openElement warns if given an element name with a space in it.
 * The implementation of buildStringCast in Wikimedia\Rdbms\Database has changed to explicitly cast. Subclasses relying on the base-class implementation should check whether they need to override it now.
 * BagOStuff::add is now abstract and must explicitly be defined in subclasses.
 * LinksDeletionUpdate is now a subclass of LinksUpdate. As a consequence, the following hooks will now be triggered upon page deletion in addition to page updates: LinksUpdateConstructed, LinksUpdate, LinksUpdateComplete. LinksUpdateAfterInsert is not triggered since deletions do not cause insertions into links tables.
 * Category::newFromID( $id )->getID will now return $id without any validation, to avoid a mostly unnecessary DB query.
 * On Special:Version, the name for an extension can no longer be arbitrary html when no link is specified.

Compatibility
MediaWiki 1.33 requires PHP 7.0.13 or later. Although HHVM 3.18.5 or later is supported, it is generally advised to use PHP 7.0.13 or later for long term support.

MySQL/MariaDB 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 and Microsoft SQL Server.

The supported versions are:


 * MySQL 5.5.8 or later
 * PostgreSQL 9.2 or later
 * SQLite 3.8.0 or later
 * Oracle 9.0.1 or later
 * Microsoft SQL Server 2005 (9.00.1399)