If the cache of CBS data maintained by Server Manager becomes corrupt, you can get “Role Error” messages when you try and open Server Manager. To try and resolve this problem, close Server Manager and delete the following two files from the %systemroot%\System32\ServerManager\Cache directory:
CbsUpdateInfo.bin
CbsUpdateState.bin
Then restart Server Manager and it should query CBS and determine the install state of the roles on the server and should recreate the two cache files you deleted.