This test involves restarting a replica set that it is connecting to with --shardsvr. The restart can cause commands to throw a FailedToSatisifyReadPreference error. The does have retry logic, through using retryWrites: true sessions to retry on retryable errors and this retryOnRetryableError helper (e.g. here) which supports taking in additional errors to retry on but currently on the renameCollection command in the DDL thread specifies an additional error (namely, ShardNotFound). However, FailedToSatisifyReadPreference is not a retryable error so it doesn't get retried by the session util or retryOnRetryableError helper. convert_to_and_from_sharded.js should be modified to correctly retry all commands inside the CRUD and DDL thread on FailedToSatisifyReadPreference.