For example, when I try to log in in beta labs:
[XQGFxqwQBHcAABxvtLIAAAAM] /wiki/Special:UserLogin Wikimedia\Rdbms\DBReadOnlyRoleError from line 1040 of /srv/mediawiki/php-master/includes/libs/rdbms/database/Database.php: Write operations are not allowed on replica database connections.
Backtrace:
#0 /srv/mediawiki/php-master/includes/libs/rdbms/database/Database.php(1249): Wikimedia\Rdbms\Database->assertIsWritableMaster()
#1 /srv/mediawiki/php-master/includes/libs/rdbms/database/DatabaseMysqlBase.php(248): Wikimedia\Rdbms\Database->executeQuery(string, string, integer)
#2 /srv/mediawiki/php-master/includes/libs/rdbms/database/Database.php(2412): Wikimedia\Rdbms\DatabaseMysqlBase->doSelectDomain(Wikimedia\Rdbms\DatabaseDomain)
#3 /srv/mediawiki/php-master/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1036): Wikimedia\Rdbms\Database->selectDomain(Wikimedia\Rdbms\DatabaseDomain)
#4 /srv/mediawiki/php-master/includes/libs/rdbms/loadbalancer/LoadBalancer.php(890): Wikimedia\Rdbms\LoadBalancer->openForeignConnection(integer, string, integer)
#5 /srv/mediawiki/php-master/includes/libs/rdbms/loadbalancer/LoadBalancer.php(763): Wikimedia\Rdbms\LoadBalancer->openConnection(integer, string, integer)
#6 /srv/mediawiki/php-master/includes/libs/rdbms/loadbalancer/LoadBalancer.php(850): Wikimedia\Rdbms\LoadBalancer->getConnection(integer, array, string, integer)
#7 /srv/mediawiki/php-master/extensions/CentralAuth/includes/CentralAuthUser.php(2485): Wikimedia\Rdbms\LoadBalancer->getConnectionRef(integer, array, string)
#8 /srv/mediawiki/php-master/extensions/CentralAuth/includes/CentralAuthUser.php(2381): CentralAuthUser->localUserData(string)
#9 /srv/mediawiki/php-master/extensions/CentralAuth/includes/CentralAuthUser.php(2354): CentralAuthUser->queryAttached()
#10 /srv/mediawiki/php-master/extensions/CentralAuth/includes/CentralAuthHooks.php(1433): CentralAuthUser->getLocalGroups()
#11 /srv/mediawiki/php-master/includes/Hooks.php(174): CentralAuthHooks::onPasswordPoliciesForUser(User, array)
#12 /srv/mediawiki/php-master/includes/Hooks.php(202): Hooks::callHook(string, array, array, NULL)
#13 /srv/mediawiki/php-master/includes/password/UserPasswordPolicy.php(180): Hooks::run(string, array)
#14 /srv/mediawiki/php-master/includes/password/UserPasswordPolicy.php(77): UserPasswordPolicy->getPoliciesForUser(User)
#15 /srv/mediawiki/php-master/includes/user/User.php(1208): UserPasswordPolicy->checkUserPassword(User, string)
#16 /srv/mediawiki/php-master/includes/auth/AbstractPasswordPrimaryAuthenticationProvider.php(106): User->checkPasswordValidity(string)
#17 /srv/mediawiki/php-master/includes/auth/TemporaryPasswordPrimaryAuthenticationProvider.php(142): MediaWiki\Auth\AbstractPasswordPrimaryAuthenticationProvider->checkPasswordValidity(string, string)
#18 /srv/mediawiki/php-master/includes/auth/AuthManager.php(455): MediaWiki\Auth\TemporaryPasswordPrimaryAuthenticationProvider->beginPrimaryAuthentication(array)
#19 /srv/mediawiki/php-master/includes/auth/AuthManager.php(385): MediaWiki\Auth\AuthManager->continueAuthentication(array)
#20 /srv/mediawiki/php-master/includes/specialpage/AuthManagerSpecialPage.php(353): MediaWiki\Auth\AuthManager->beginAuthentication(array, string)
#21 /srv/mediawiki/php-master/includes/specialpage/AuthManagerSpecialPage.php(482): AuthManagerSpecialPage->performAuthenticationStep(string, array)
#22 /srv/mediawiki/php-master/includes/htmlform/HTMLForm.php(672): AuthManagerSpecialPage->handleFormSubmit(array, VFormHTMLForm)
#23 /srv/mediawiki/php-master/includes/specialpage/AuthManagerSpecialPage.php(416): HTMLForm->trySubmit()
#24 /srv/mediawiki/php-master/includes/specialpage/LoginSignupSpecialPage.php(313): AuthManagerSpecialPage->trySubmit()
#25 /srv/mediawiki/php-master/includes/specialpage/SpecialPage.php(571): LoginSignupSpecialPage->execute(NULL)
#26 /srv/mediawiki/php-master/includes/specialpage/SpecialPageFactory.php(575): SpecialPage->run(NULL)
#27 /srv/mediawiki/php-master/includes/MediaWiki.php(288): MediaWiki\Special\SpecialPageFactory->executePath(Title, RequestContext)
#28 /srv/mediawiki/php-master/includes/MediaWiki.php(865): MediaWiki->performRequest()
#29 /srv/mediawiki/php-master/includes/MediaWiki.php(515): MediaWiki->main()
#30 /srv/mediawiki/php-master/index.php(42): MediaWiki->run()
#31 /srv/mediawiki/w/index.php(3): include(string)
#32 {main}