Hello, In my network, hundrets RouterBoards, I manage users by usermanager and everything works fine except Bandwidthtest. I am getting "auth error/failed" hence I've got question does sombody know if it is a configuration error or it is related to the system problem. Can Bandwithtest use radius users? I will be thankful for any help.

If you use RADIUS for login to router than you can use UM users for bandwithtest, I think.

If you use User Manager to authenticate RouterOS users, you need to make sure that the mikrotik-group setting is a group that allows "test" policy. Also check what you have under "default group" if you have not specified a group in the UM:

http://wiki.mikrotik.com/wiki/Manual:Router_AAA