Been struggling to update my IBP install for ages now and none of the support so far has been able to address the problem.
When I try to do an automatic upgrade, I get an error about the PHP version needing to update. But when I update the PHP version, the entire site crashes and returns 500 errors on every page including the admin.
To try and get around this, I tried to do a manual upgrade by changing to PHP 8.1 and then copying the new files to the server. However, after doing so if I go to domain.com/admin/upgrade - the upgrade process starts and then immediately returns another 500 error and cannot proceed.
I've looked at the error logs and prior to the manual update attempt there were references to the theme.php, however, no new errors are being logged during these crashes.
I've tried just about everything and cannot get our site to upgrade, we're now massively behind in updates because of this.