Error while converting a Cluster into a Replica Set

We followed the instructions to Convert a Cluster with a Single Shard into a Replica Set but as soon as we restarted the first Secondary (of a total of 3 secondaries + 1 primary) without the --shardsvr option, all database clients (which are connecting already directly to the replSet without problems instead to the mongoS routers) received the following error while querying the database:

Query failed with error code 211 and error message 'Cache Reader No keys found for HMAC that is valid for time: { ts: Timestamp(1585205456, 422) } with id: 6802955028354040016' on server

Therefore, we have immediately reversed the change.
This error makes it impossible for us to convert the single-shard cluster into a standalone replSet.
How to proceed?


Hi, Kay! Did you ever find a solution to this problem? I’m hitting the same error but in a somewhat different scenario: I have a replica set (not a sharded cluster) using the MMAPv1 engine and am switching to WiredTiger. As soon as I add a new node running WiredTiger, I hit this error in my application.