In 2.x, an unacknowledged write operation on DBCollection returns a WriteResult, and any access to the WriteResult properties will trigger a call to the getlasterror command on the same socket, which is likely to fail with an exception.

In 3.x we will no longer call getlasterror, and instead DBCollection returns a null WriteResult for any unacknowledged writes. This ticket proposes to change DBCollection to be closer to 2.x: return a WriteResult, but throw an exception from all property accessors.