Issue when I try to save group images to a group album

[Dave]

The error happens in /includes/class_core.php line 4684, which is the template rendering function.
So in one of the templates that renders that page, there's a syntax error.

I would test it in different forum styles to determine if it's a style or a different issue. If it does not happen on a different forum style, check the differences between the templates that are used on that page. If it does happen on all forum styles, it's probably the PHP version causing it but we can probably fix it if you find the offending template and paste it here.

The "Not Acceptable" error is caused by Mod_Security, which is a security extension for Apache. You can disable this in CPanel/WHM or ask your host.