App crashing with MongoErrors on Galaxy

My app just suddenly became unresponsive, looking in the Galaxy logs it was full of these two errors:

Exception while polling query { ... } MongoError: Pool was force destroyed
Exception while polling query { ... } MongoError: no primary server available

Killing the container solved the issue, but I have no idea what caused it or how to prevent it happening again. Can anybody help me with this?

I’m running on Galaxy and Mongo Atlas (M0), meteor@1.9.3, mongo@1.10.0.

I had a similar issue while not on Galaxy with those same error logs, after working with Mongo support we determined that the op log had gotten backed up and caused a node to desync. The solution was to increase the configured Oplog Size, it had a default of 990mb so i increased it to 6gb.