Collection [local.oplog.rs] not found issue when restarting mongod for setting up replica set

Question

I have followed the official documentation for converting the standalone mongodb instance (local ubuntu machine) to replica set. The part where we restart mongod with --replset flag seems to invite an error.

Command used:

sudo systemctl stop mongod

sudo mongod --port 27017 --dbpath /var/lib/mongodb --replSet rs1 --bind_ip localhost

{"t":{"$date":"2023-11-24T17:58:28.002+05:30"},"s":"W",  "c":"QUERY",    "id":23799,   "ctx":"ftdc","msg":"Aggregate command executor error","attr":{"error":{"code":26,"codeName":"NamespaceNotFound","errmsg":"Unable to retrieve storageStats in $collStats stage :: caused by :: Collection [local.oplog.rs] not found."},"stats":{},"cmd":{"aggregate":"oplog.rs","cursor":{},"pipeline":[{"$collStats":{"storageStats":{"waitForLock":false,"numericOnly":true}}}],"$db":"local"}}}

The cmd goes into a loop printing this message again and again, till I force close the program.

I have tried reinstalling mongodb to see if it is a random issue. But it prevails nevertheless.

Tried multiple variations of the mongod restart command. Used different shutdown procedures.

Annettannetta

That error is probably expected until you rs.inititate(). Better question for dba site – Than

I forgot to mention that the whole process goes into a loop and we need to force close it by typing Ctrl+C. Due to this issue, Mongod will not spin up. So, I cannot enter the shell and execute the initiate() function. On top of that, Mongod will remain shut down even if I try to start the service. I then reinstall MongoDB to obtain a working service. – Annettannetta

Answer 1

I had the same problem when trying to connect with Compass.

But I was able to run mongosh on the server's shell, and then run rs.initiate() from there.

Once rs.initiate() was finished, I am able to connect with Compass to all of the nodes in the replication set and verify replication is working.

Margetts

Also the local.oplog.rs stopped appearing in the log. – Margetts