Looks to me like your Couchbase Server is responding slow, and therefor the client gets a timeout which is uncaught and therefor bubbles up to show up in the console. I guess there is some configuration setup so your server maybe runs out of memory for the bucket you are using and therefor swaps to disk? Or your server has a bad connection to the Couchbase Server which causes the timeouts? This is just a first guess, hope I can help more with more details on the setup.