I have been having the same issue over the last week with a Windows Service that was recently upgraded to .Net client 2.1.3. Restarting the service fixes the problem when it occurs.
It appears to be specific to the running application, none of the other applications have the problem at the same time. In fact, the exact same service running on other servers in the the farm against the exact same cluster will be working fine. This makes me believe that it’s an issue in the .Net client.
This is running against a 3.1 cluster running on Amazon Linux. The client service is running on Windows Server 2012 and .Net 4.5.2. No rebalance is being performed on the cluster when the errors occur.
I have also reviewed the commits for client 2.1.4 and don’t see any changes since 2.1.3 that look like they would prevent this problem. However, it looks like this commit https://github.com/couchbase/couchbase-net-client/commit/30e46f051a3c57b0c7f06dc4938482b610cb4362 might change the error behavior and make it return Success = false and an Exception object, rather than throwing an exception. Not sure if I’m reading that right, though.
@jmorris do you have any thoughts on this one?
Brant