Seems to work now. Unfortunately there is one more logged error that appeared on xenforo:
ErrorException: [E_NOTICE] Array to string conversion src/XF/Db/Mysqli/Statement.php:63
Generated by: kalle Jan 11, 2018 at 6:14 AM
Stack trace
#0 [internal function]: XF::handlePhpError(8, '[E_NOTICE]...