Replication problem with Couchbase server 6.6.1

Hi, I have a problem with replication from server A to B. There is configured replication on a bucket between two servers, and if i create a new document it is not replicated. If I remove the bucket on target host and recreate replication for it all the documents are successfully replicated. At some point after creating new documents they again stop randomly being replicated. I checked the goxdrc.log and noticed that the counter “docs_failed_cr_source” is increased.
Could anybody give advice what logs to check, what could be the issue.
Any suggestion would be helpful. Thank you in advance.

Number of documents that have failed conflict resolution on the source cluster and not replicated to target cluster.

Hi hyunjuV, thank you very much for the reply. I saw that counter in the documentation, but the one thing is unclear why this conflict occurs on target server nobody is doing updates or create a new document. Why it is saying about conflicts of seq number. If I check the seq number on target host it is smaller than the seq number of new documents on the source.

Deletions or expirations can cause tombstones and can lose in a conflict resolution.
If the target is target to another source, that can cause the original source to lose too.