The merge process failed because it detected a mismatch between the replication metadata of the two replicas, such that some changes could be lost leading to non-convergence. This could be due to the subscriber not synchronizing within the retention period, or because one of the replicas was restored to a backup older than retention period, or because the publisher performed more aggressive cleanup on articles of type download-only and articles with partition_options = 3.
The merge process failed because it detected a mismatch between the replication metadata of the two replicas. This means that some changes could be lost, which could cause non-convergence.
Restore the replica to a more recent backup, or reinitialize the merge process without uploading data first.