The "dbHash" command, by using a long-running snapshot read with $_internalReadAtClusterTime, has the tendency to induce cache pressure.

When application threads are performing eviction and the WiredTiger cache gets stuck, WiredTiger will abort the oldest transaction in order to make progress. This error manifests as a WT_ROLLBACK error code, and then MongoDB converts this to a WriteConflictException.

For that reason, it would be expected for dbHash to get WriteConflicts occasionally, and we should have logic to retry or ignore failures in this case.