It looks something like this:
[Wz03lFwtCOv-yYg8e1qVvgAAAY4] /mw19/ Wikimedia\Rdbms\DBQueryError from line 1149 of /home/gjlxrtap/public_html/mw19/includes/libs/rdbms/database/Database.php: A database query error has occurred. Did you forget to run your application's database schema updater after upgrading?
Query: SELECT user_id,user_name,user_real_name,user_email,user_touched,user_token,user_email_authenticated,user_email_token,user_email_token_expires,user_registration,user_editcount FROM `gjlxrtap_mw19758`.`mwd50q_user` WHERE user_id = '1' LIMIT 1
Function: User::loadFromDatabase
Error: 1142 SELECT command denied to user 'gjlxrtap_wiki2'@'localhost' for table 'mwd50q_user' (localhost)
Backtrace:
#0 /home/gjlxrtap/public_html/mw19/includes/libs/rdbms/database/Database.php(979): Wikimedia\Rdbms\Database->reportQueryError(string, integer, string, string, boolean)
#1 /home/gjlxrtap/public_html/mw19/includes/libs/rdbms/database/Database.php(1343): Wikimedia\Rdbms\Database->query(string, string)
#2 /home/gjlxrtap/public_html/mw19/includes/libs/rdbms/database/Database.php(1411): Wikimedia\Rdbms\Database->select(string, array, array, string, array, array)
#3 /home/gjlxrtap/public_html/mw19/includes/user/User.php(1287): Wikimedia\Rdbms\Database->selectRow(string, array, array, string, array)
#4 /home/gjlxrtap/public_html/mw19/includes/user/User.php(496): User->loadFromDatabase(integer)
#5 /home/gjlxrtap/public_html/mw19/includes/libs/objectcache/WANObjectCache.php(892): User->{closure}(boolean, integer, array, NULL)
#6 [internal function]: WANObjectCache->{closure}(boolean, integer, array, NULL)
#7 /home/gjlxrtap/public_html/mw19/includes/libs/objectcache/WANObjectCache.php(1012): call_user_func_array(Closure, array)
#8 /home/gjlxrtap/public_html/mw19/includes/libs/objectcache/WANObjectCache.php(898): WANObjectCache->doGetWithSetCallback(string, integer, Closure, array, NULL)
#9 /home/gjlxrtap/public_html/mw19/includes/user/User.php(521): WANObjectCache->getWithSetCallback(string, integer, Closure, array)
#10 /home/gjlxrtap/public_html/mw19/includes/user/User.php(441): User->loadFromCache()
#11 /home/gjlxrtap/public_html/mw19/includes/user/User.php(405): User->loadFromId(integer)
#12 /home/gjlxrtap/public_html/mw19/includes/session/UserInfo.php(88): User->load()
#13 /home/gjlxrtap/public_html/mw19/includes/session/CookieSessionProvider.php(119): MediaWiki\Session\UserInfo::newFromId(string)
#14 /home/gjlxrtap/public_html/mw19/includes/session/SessionManager.php(487): MediaWiki\Session\CookieSessionProvider->provideSessionInfo(WebRequest)
#15 /home/gjlxrtap/public_html/mw19/includes/session/SessionManager.php(190): MediaWiki\Session\SessionManager->getSessionInfoForRequest(WebRequest)
#16 /home/gjlxrtap/public_html/mw19/includes/WebRequest.php(735): MediaWiki\Session\SessionManager->getSessionForRequest(WebRequest)
#17 /home/gjlxrtap/public_html/mw19/includes/session/SessionManager.php(129): WebRequest->getSession()
#18 /home/gjlxrtap/public_html/mw19/includes/Setup.php(762): MediaWiki\Session\SessionManager::getGlobalSession()
#19 /home/gjlxrtap/public_html/mw19/includes/WebStart.php(114): require_once(string)
#20 /home/gjlxrtap/public_html/mw19/index.php(40): require(string)
#21 {main}