What this message means is that something is trying to make updates to a document revision but that revision has been “compacted away” because it was no needed by Sync Gateway for anything. For example, it may have been a non-leaf revision, and the later leaf revision was sufficient to keep around, so Sync Gateway threw away the the non-leaf revision since it added no value. Then later, something tried to push an update to Sync Gateway based on that (stale) revision that no longer exists in the system, and hence that error was seen.
It’s hard to tell without more context if that was happening from a Couchbase Lite client or the Sync Gateway bucket shadowing process.
i think its because i resolved conflicts in side mobile app but when i did the process i followed the documentation of couchbase