MongoDB Error: “not authorized for query on admin.system.users”

Question

How to setup authentication on MongoDB using the following configuration ?

2 mongoD instances, sharded collections.
1 mongoS instance on another server.
1 mongoD as a config server.

Whenever a turn on auth on mongod, i'm not enabled to logon on any servers, the users are created but i still can't login. The following error appear when trying to logon on mongoS instance:

Answer 1

If you have a problem like I had it is likely that you could not query anything (with similar messages that you are not authorized).

By accident I noticed if I run two different versions of mongo daemon (win7/ent) second daemon starts but does not care if other mongo is listening, so it is unclear which daemon takes requests.

When I stopped all daemons and started one, everything started working. (for me)