The problem was an old XGL configuration that had belonged to Egdy. I removed it from /etc/gdm/gdm.conf-custom, and now there is no problem anymore.
However, I found the error message quite confusing. Of course there is no file named "custom.conf", so the "Make sure that the file exists" looks quite logical. However I tried to touch the file, copied my gdm .conf-custom to "custom.conf" and tried a lot of other things before I looked into the configuration itself. So the error message should be different. I saw in the forum that others have similar issues with older XGL configurations. -- gdmsetup does not work, lacks custom.conf https://launchpad.net/bugs/84458 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
