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 our-db-server.domain.com:27017

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?
Thanks!

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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.

I couldn’t post more than two links on this forum so you can check out what I discovered on stackoverflow: Error while converting a mongoDB Cluster into a Replica Set - Stack Overflow.

My situation is identical to Noach_Magedman’s. Could potentially be an issue related to MMAP.

It’s likely the client library for connecting to MongoDB is getting caught in some sort of expired clusterTime loop and is not correctly updating its clusterTime when receiving these errors. Perhaps disconnecting and finding a different node would help.