MediaWiki internal error.

Original exception: exception 'DBQueryError' with message 'A database error has occurred. Did you forget to run maintenance/update.php after upgrading? See: https://www.mediawiki.org/wiki/Manual:Upgrading#Run_the_update_script
Query: COMMIT
Function: SiteStatsUpdate::doUpdate
Error: 1213 Deadlock: wsrep aborted transaction (192.168.42.42:3307)
' in /var/www/ISWiki/prod/releases/20190826144318/lib/includes/db/Database.php:918
Stack trace:
#0 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/db/Database.php(885): DatabaseBase->reportQueryError('Deadlock: wsrep...', 1213, 'COMMIT', 'SiteStatsUpdate...', false)
#1 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/db/Database.php(2871): DatabaseBase->query('COMMIT', 'SiteStatsUpdate...')
#2 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/SiteStats.php(273): DatabaseBase->commit('SiteStatsUpdate...')
#3 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/DeferredUpdates.php(70): SiteStatsUpdate->doUpdate()
#4 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/Wiki.php(408): DeferredUpdates::doUpdates('commit')
#5 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/Wiki.php(594): MediaWiki->finalCleanup()
#6 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/Wiki.php(503): MediaWiki->main()
#7 /var/www/ISWiki/prod/releases/20190826144318/lib/index.php(58): MediaWiki->run()
#8 {main}

Exception caught inside exception handler: exception 'DBUnexpectedError' with message 'Error in numRows(): WSREP has not yet prepared node for application use (192.168.42.42:3307)' in /var/www/ISWiki/prod/releases/20190826144318/lib/includes/db/DatabaseMysql.php:234
Stack trace:
#0 /var/www/ISWiki/prod/releases/20190826144318/lib/extensions/SemanticForms/includes/SF_Utils.php(124): DatabaseMysql->numRows(false)
#1 /var/www/ISWiki/prod/releases/20190826144318/lib/extensions/SemanticForms/includes/SF_FormLinker.php(313): SFUtils::getCategoriesForPage(Object(Title))
#2 /var/www/ISWiki/prod/releases/20190826144318/lib/extensions/SemanticForms/includes/SF_FormEditAction.php(64): SFFormLinker::getDefaultFormsForPage(Object(Title))
#3 /var/www/ISWiki/prod/releases/20190826144318/lib/extensions/SemanticForms/includes/SF_FormEditAction.php(151): SFFormEditAction::displayTab(Object(SkinIswiki), Array)
#4 [internal function]: SFFormEditAction::displayTab2(Object(SkinIswiki), Array)
#5 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/Hooks.php(216): call_user_func_array('SFFormEditActio...', Array)
#6 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/GlobalFunctions.php(3859): Hooks::run('SkinTemplateNav...', Array)
#7 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/SkinTemplate.php(981): wfRunHooks('SkinTemplateNav...', Array)
#8 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/SkinTemplate.php(455): SkinTemplate->buildContentNavigationUrls()
#9 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/OutputPage.php(1982): SkinTemplate->outputPage()
#10 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/Exception.php(182): OutputPage->output()
#11 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/Exception.php(209): MWException->reportHTML()
#12 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/Exception.php(490): MWException->report()
#13 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/Exception.php(569): MWExceptionHandler::report(Object(DBQueryError))
#14 /var/www/ISWiki/prod/releases/20190826144318/lib/includes/Wiki.php(506): MWExceptionHandler::handle(Object(DBQueryError))
#15 /var/www/ISWiki/prod/releases/20190826144318/lib/index.php(58): MediaWiki->run()
#16 {main}