Add $wgDiffEngine

[lhc/web/wiklou.git] / 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.1 ===
* $wgDiffEngine (T237049) – This configuration can be used to specify which
  difference engine to use. MediaWiki continues to default to automatically
  choosing the first of $wgExternalDiffEngine, wikidiff2, or php that is
  usable.

== MediaWiki 1.34.0-rc.1 ==

=== Changes since MediaWiki 1.34.0-rc.0 ===
* (T231742) rdbms: Restore debug toolbar "Queries" feature.
* (T231366) The ProfilerOutputDb class, 'profiling' table, and profileinfo.php
  entry point had been deprecated.
* (T234361) localisation: Add debug message for backend of MessageCache.
* (T234361) session: Add debug message for the used store class.
* (T235559) Fix example Kask configuration in RESTBagOStuff class comment.
* (T235137) Don't apply styling for Special:Contributions on other pages.
* Upgrade mediawiki-codesniffer from 26.0.0 to 28.0.0 (dev-only).
* (T219604) The "jquery.ui.*" and "jquery.effects.*" modules are now
  deprecated as aliases for the "jquery.ui" module.
* (T235392) Deprecate setting Parser::mTitle to null.
* Supporting commits for T235392 were also backported to prevent divergence
  from master (MediaWiki 1.35).
* (T234581) The 'jquery.tabIndex' module is deprecated.
* Fix docs for GetUserBlock hooks.
* Parser: Hard deprecate getConverterLanguage.
* (T236810) A number of public methods of Parser were exposed only for
  historical reasons and have been deprecated: doMagicLinks,
  doDoubleUnderscore, doHeadings, doAllQuotes, replaceExternalLinks,
  replaceInternalLinks, replaceInternalLinks2, getVariableValue,
  initialiseVariables, formatHeadings, testPst, testPreprocess, testSrvus,
  areSubpagesAllowed, maybeDoSubpageLink, splitWhitespace, createAssocArgs,
  armorLinks, makeKnownLinkHolder, getImageParams, parseLinkParameter,
  stripAltText, replaceLinkHolders, replaceLinkHoldersText, armorLinks,
  makeKnownLinkHolder, getImageParams, parseLinkParameter, stripAltText.
* (T30798) $wgServer must now always be set in LocalSettings.php. This is most
  likely the case already for any wiki installed after 1.18. The autodetection
  system was informally deprecated since 1.18 and vulnerable to cache poisoning
  attacks. Older wikis may need to update their LocalSettings.php file.
* (T232169) Hard deprecate $wgSysopEmailBans.
* (T236628) Fix for ArticleRevisionViewCustom hook in DifferenceEngine.php.
* (T181658) Do not insert page titles into querycache.qc_value.
* ParamValidator has been flagged as unstable.
* Hard deprecate Parser::disableCache().

== MediaWiki 1.34.0-rc.0 ==

== 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.
* (T30798) $wgServer must now always be set in LocalSettings.php. This is most
  likely the case already for any wiki installed after 1.18. The autodetection
  system was informally deprecated since 1.18 and vulnerable to cache poisoning
  attacks. Older wikis may need to update their LocalSettings.php file.
* 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 $wgDebugLogGroups['profileoutput'].
* $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.

=== External library changes in 1.34 ===

==== 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 28.0.0 (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 ===
* 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:
  * CryptRand class
  * CryptRand service
  * Functions of the MWCryptRand class: singleton(), wasStrong() and generate().
* Various Special Page PHP Classes were renamed (mostly casing changes):
  * 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
* 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 $_GET.
* The selectFields() methods on classes LocalFile, ArchivedFile, OldLocalFile,
  DatabaseBlock, and RecentChange, deprecated in 1.31, have been removed. Use
  the corresponding getQueryInfo() methods instead.
* The following methods on Revision, deprecated since 1.31, have been removed.
  Use RevisionStore::getQueryInfo() or RevisionStore::getArchiveQueryInfo()
  instead.
  * Revision::userJoinCond()
  * Revision::pageJoinCond()
  * Revision::selectFields()
  * Revision::selectArchiveFields()
  * Revision::selectTextFields()
  * Revision::selectPageFields()
  * Revision::selectUserFields()
* User::setNewpassword(), deprecated in 1.27 has been removed.
* The ObjectCache::getMainWANInstance and ObjectCache::getMainStashInstance
  functions, deprecated since 1.28, have been removed.
* Language::$dataCache has been removed (without prior deprecation, for
  practical reasons). Use MediaWikiServices instead to get a LocalisationCache.

=== Deprecations in 1.34 ===
* 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 ProfilerOutputDb class, 'profiling' table, and profileinfo.php entry
  point had been deprecated (T231366).
* 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.
* The 'jquery.tabIndex' module is 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
  $wgGroupPermissions['sysop']['blockemail'] = true;
* 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.)
* Using the Parser without initializing its $mTitle property to non-null has
  been deprecated.  In a future release Parser::getTitle() will throw a
  TypeError if $mTitle is uninitialized.
* A number of public methods of Parser were exposed only for historical
  reasons and have been deprecated: doMagicLinks, doDoubleUnderscore,
  doHeadings, doAllQuotes, replaceExternalLinks, replaceInternalLinks,
  replaceInternalLinks2, getVariableValue, initialiseVariables, formatHeadings,
  testPst, testPreprocess, testSrvus, areSubpagesAllowed, maybeDoSubpageLink,
  splitWhitespace, createAssocArgs, armorLinks, makeKnownLinkHolder,
  getImageParams, parseLinkParameter, stripAltText, replaceLinkHolders,
  replaceLinkHoldersText, armorLinks, makeKnownLinkHolder, getImageParams,
  parseLinkParameter, stripAltText.

=== 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.
* (T232563) Browser support ("Grade C") for Internet Explorer 6 and 7
  was discontinued. Basic content and security features may no longer
  work correctly in these browsers.

== 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.