Did anybody have this issue? There is no GroupList_DeleteCommand methods in the EPIServer.UI.Admin.AdminGroup?
Sounds like you either have a version mismatch somehow (between the UI files and the assembly versions loaded), or you have a customized admingroup.aspx which isn't working correctly.
Thanks. I had to reinstall the cms core.
Did anybody have this issue? There is no GroupList_DeleteCommand methods in the EPIServer.UI.Admin.AdminGroup?