Trying to log in to the new CCS Management Console, and you see either of these error messages.
An error occurred while logging in. Contact your administrator.
OR
Insufficient permissions. Contact your administrator.
CCS 12.7+
Verify that the user(s) is in the local IIS_IUSRS group on the Application Server where the IIS server is being hosted.
Next verify the users are in a single valid role within CCS. You may need to remove the user from their role and re-add them back in.
You can use the Export Tasks -> Roles to Users drop down from the Roles workspace to help identify if the user is more than 1 role.
Once the user is in the IIS_IUSRS group and have a valid role in CCS, they will now be able to log in.