DBException handling request, closing client connection

Erwin_Grunwald · August 13, 2020, 12:37pm

When building a new 4.2.8 (3 nodes w/ 1 Arbiter), I’m seeing the following in the primary & secondary log file:

2020-08-13T12:20:02.035+0000 I NETWORK [listener] connection accepted from 10.93.57.24:44784 #175 (17 connections now open)
2020-08-13T12:20:02.036+0000 E - [conn175] Assertion: Location34348: cannot translate opcode 2010 src/mongo/rpc/message.h 120
2020-08-13T12:20:02.036+0000 I NETWORK [conn175] DBException handling request, closing client connection: Location34348: cannot translate opcode 2010
2020-08-13T12:20:02.036+0000 I NETWORK [conn175] end connection 10.93.57.24:44784 (16 connections now open)

Any ideas?

Erwin_Grunwald · August 17, 2020, 8:33pm

Per the error message in the mongod.log: Assertion: Location34348: cannot translate opcode 2010 src/mongo/rpc/message.h 120

I found this.

github.com

mongodb/mongo/blob/master/src/mongo/rpc/message.h

/**
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kevinadi · August 20, 2020, 6:20am

Hi @Erwin_Grunwald, welcome to the community.

I think what caused the error message is a client that somehow sending a message that the server cannot understand. It appears that the client in question is identified as [conn175] from 10.93.57.24. Are you seeing any issue in the server’s operation that’s connected to these messages? Could you check how that client is connecting to the server?

(3 nodes w/ 1 Arbiter)

On another note, I would recommend against using an arbiter in this setup. A replica set needs an odd number of nodes to facilitate voting, and the arbiter is not adding value here since you already have 3 data bearing members. See Replica Set Deployment Architectures for a more detailed explanation.

Best regards,
Kevin

Erwin_Grunwald · August 20, 2020, 1:29pm

Thanks Kevin. I will take a look.

BTW, when I said (3 nodes w/ 1 Arbiter)… I should have said (3 nodes w/ one being an Arbiter). I do have an old number of nodes in the cluster.