96: OperationFailed

What does it mean?

A generic operation failure; an unexpected error occurred while the command was running and the operation could not complete. It is the generic error used when no more specific code exists.

Why does it happen?

A server-side internal error, resource exhaustion, an inconsistent state, a subsystem failure (storage, replication), or various failure conditions specific to a particular command.

How to fix it

Determine the root cause by examining the full error message text and the server logs (mongod.log). Retry the operation; the condition may be transient. Check resources (disk, memory) and replica set health. If the problem recurs, review the command and its input data.