Merge "Update special page aliases for Serbian"

[lhc/web/wiklou.git] / RELEASE-NOTES-1.33

= MediaWiki 1.33 =

== MediaWiki 1.33.0-PRERELEASE ==

THIS IS NOT A RELEASE YET

MediaWiki 1.33 is a pre-release testing branch, and is not recommended for use
in production.

== 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.

=== Configuration changes for system administrators in 1.33 ===

==== 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.

=== External library changes in 1.33 ===

==== New external libraries ====
* Added wikimedia/password-blacklist 0.1.4.
* Added guzzlehttp/guzzle 6.3.3.
* Added jakub-onderka/php-console-highlighter 0.3.2 explicitly (dev-only).

==== Changed external libraries ====
* Updated OOUI from v0.29.2 to v0.31.2.
* 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 wikimedia/ip-set from 1.2.0 to 2.0.1.
  * The deprecated IPSet\IPSet alias was removed, Wikimedia\IPSet must be
    used instead.
* Updated qunitjs from 2.6.2 to 2.9.1.
* Updated jquery-client from 2.0.1 to 2.0.2.
* 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 pear/net_smtp from 1.8.0 to 1.8.1.
* Updated cssjanus/cssjanus from 1.2.0 to 1.2.1.
* 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.

=== 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.

=== 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)

== 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.