https://www.ubbcentral.com/forums/u...defined-function-resize-image#Post218328Just go into the gallery section of the control panel, verify the settings, and submit that page. Until you choose and submit the gallery settings page it doesn't know what image library it should be using. That will also tell you if gd2 is available.
If its not this, there are three things to confirm:
1) Can GD2 be located?
Control Panel > PHP Info
Scroll down to the GD section, and check if its enabled. And if you are running GD 2.3, check in that same section, that you are running a GD 2.1 compatible version of GD 2.3. If you're running a windows server, you may have to manually install it yourself.
2) Check that you are allowing the proper file extension, ".gif,.jpg,.txt,.zip,.png" Separated with a comma. No spaces.
Control Panel > Feature Settings > Attachments
3) In the same place as the last one, this probably isnt the case, but check if your directories are correct and writable.
Control Panel > Feature Settings > Attachments
I believe the UBB.threads temporary directory for all image processing is located at {$config['FULL_PATH']}/tmp/ (hardcoded/cannot be changed). Through FTP, check that the correct permissions are set.
