RetryLoop for GetAndTouchRaw with key

I am getting following error in sync gateway.

RetryLoop for GetAndTouchRaw with key _sync:local:e14a287c59cabde1cf109d1aac9c99bc4c6d9c57 giving up after 11 attempts – base.RetryLoop() at util.go:352

What can be the issue, please help.
sync gateway version is 2.1.1 and couchbase 6.0

Regards
Pankaj Sharma

There will be more information in the logs related to this error than just that line. It could be a timeout trying to write the doc to couchbase server for example.