Comment 7 for bug 236305

I just had this issue on 8.10.

To clarify: As a result of creating the user "admin" in the users-admin program, the admin group in /etc/group gets replaced by a new admin group with a new gid. All of the users originally part of the admin group are obviously no longer a part of the admin group.

As a quick fix I ended up editing the /etc/group file using the only user I could (the newly created admin user) and adding "admin" and other administration users back into the admin group.

When logged in as admin before I had corrected /etc/group, I was getting an "unexpected error" in the users-admin program when I tried to "Unlock" it. Also the "Add/Remove..." menu item instantly disappeared as soon as I added it using the menu editor. Both of these issues were gone as soon as I put the new admin user in the admin group in /etc/group.

As suggested above. To fix this issue a simple check could be performed in the users-admin program to make sure a group doesn't exist already before it is created in /etc/group.