This is what they tell me about the technical support of the hosting
#Start of the appointment#
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[24-Jul-2019 10:41:59 UTC] PHP Fatal error: Uncaught RuntimeException: SplFileInfo::isFile(): open_basedir restriction in effect. File(/tmp/.s.PGSQL.5432) is not within the allowed path(s): (/home/oax:/home2/oax:/usr/lib/php:/usr/local/lib/php:/usr/local/php7:/usr/local/php55:/usr/local/php54:/usr/local/php53:/usr/local/php52:/tmp:/opt/alt/php70) in /home/oax/public_html/ostickets/upload/include/mpdf/vendor/mpdf/mpdf/src/Cache.php:92
The file you are trying to access is: /tmp/.s.PGSQL.5432
This is not even a file, if not a symbolic link from PostgreSQL, a database system that is not available on the server.
Is it possible that the version you use of OsTicket requires PostgreSQL or something similar? Actually if you do not require PostgreSQL the application should not access that symbolic link at any time, and if it does, it should not "break" its operation since it is normal that it does not work.
#End of the appointment#
Thank you