I can give more information now, nobody is doing bad things on my forum. Today I got a PM from a member that cannot access the forum from mobile, he has no problems using the forum from PC. It's related to the old problem I already reported here https://www.elkarte.net/community/index.php?topic=5282 I told him to clear the browser cookies and temporary files and he will solve. I already had this problem with other members, and the only solution I found is to clear the browser cookies and temporary files.
I checked all the logs (access, error, apache) he did nothing strange, just went to my domain and then clicked on a topic then he saw that error reported in the other topic.
There is no error in apache error log, while in php error log I see:
[27-Feb-2019 07:18:15 Europe/Rome] PHP Fatal error: Uncaught Elk_Exception: The database value you're trying to insert does not exist: group_list in /srv/users/serverpilot/apps/skodaclub/public/sources/database/Db-abstract.class.php:404
Stack trace:
#0 /srv/users/serverpilot/apps/skodaclub/public/sources/database/Db-abstract.class.php(102): Database_Abstract->error_backtrace('The database va...', 'The database va...', 256, '/srv/users/serv...', 1231)
#1 [internal function]: Database_Abstract->replacement__callback(Array)
#2 /srv/users/serverpilot/apps/skodaclub/public/sources/database/Db-mysql.class.php(168): preg_replace_callback('~{([a-z_]+)(?::...', Array, '\n\t\tSELECT b.id_...')
#3 /srv/users/serverpilot/apps/skodaclub/public/sources/Security.php(1231): Database_MySQL->query('', '\n\t\tSELECT b.id_...', Array)
#4 /srv/users/serverpilot/apps/skodaclub/public/sources/subs/Moderation.subs.php(250): boardsAllowedTo(Array)
#5 /srv/users/serverpilot/apps/skodaclub/public/themes/default/Theme.php(846): loadModeratorMenuCounts()
#6 /srv/users/serverpilot/apps/sko in /srv/users/serverpilot/apps/skodaclub/public/sources/database/Db-abstract.class.php on line 404
I did post the log exactly as it is, without editing the paths. It's strange that the path in the line #6 seems incomplete.
Any suggestion? Thank you