Turning on debug mode with notices, the only warnings that pop up are related to /include/functions.inc.php.
/include/functions.inc.php
Warning line 3613: Trying to access array offset on value of type null
Warning line 3615: Trying to access array offset on value of type null
Warning line 3634: Trying to access array offset on value of type null
Warning line 3649: Trying to access array offset on value of type null
Warning line 3649: Trying to access array offset on value of type null
Warning line 3649: Trying to access array offset on value of type null
Warning line 3659: Trying to access array offset on value of type null
Warning line 3659: Trying to access array offset on value of type null
Warning line 3659: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3613: Trying to access array offset on value of type null
Warning line 3615: Trying to access array offset on value of type null
Warning line 3634: Trying to access array offset on value of type null
Warning line 3649: Trying to access array offset on value of type null
Warning line 3649: Trying to access array offset on value of type null
Warning line 3649: Trying to access array offset on value of type null
Warning line 3659: Trying to access array offset on value of type null
Warning line 3659: Trying to access array offset on value of type null
Warning line 3659: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3613: Trying to access array offset on value of type null
Warning line 3615: Trying to access array offset on value of type null
Warning line 3634: Trying to access array offset on value of type null
Warning line 3649: Trying to access array offset on value of type null
Warning line 3649: Trying to access array offset on value of type null
Warning line 3649: Trying to access array offset on value of type null
Warning line 3659: Trying to access array offset on value of type null
Warning line 3659: Trying to access array offset on value of type null
Warning line 3659: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3679: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
Warning line 3688: Trying to access array offset on value of type null
I don't use bridging, but could take a look at the file and anything more known would help.
Thank you for the offer. I use the standard mybb.inc.php bridge file, and have the following site structure:
domain.com/forums
domain.com/gallery
The problem started appearing after I updated to PHP 8.1 - I was on PHP 7.4 before. And it's triggered when Coppermine attempts to retrieve the groups which the current user is a part of - in the function in question, an integer (100) is added to a string.
Let me know if you can think of anything else.