If a Mongo object in a shell process performs an operation as the __system user, it will receive a clusterTime with an empty signature. Currently, every Mongo object in the shell will gossip this signature to every server in the cluster. However, if one of these objects is not authenticated as __system, the server will reject the signature, and its commands will begin failing.

This can be prevented by making each Mongo object maintain its own independent store of clusterTime, which are not process global.