Kibana Error: Discover: Unable to parse/serialize body

I am getting the following error. I haven't changed anything about my setup. What causes the error. I tried googling but nothing seems to solve the problem.

rror: Unable to parse/serialize body
at respond (http://kibana.csp/bundles/kibana.bundle.js:76140:18)
at checkRespForFailure (http://kibana.csp/bundles/kibana.bundle.js:76123:8)
at http://kibana.csp/bundles/kibana.bundle.js:74738:6
at processQueue (http://kibana.csp/bundles/commons.bundle.js:42339:29)
at http://kibana.csp/bundles/commons.bundle.js:42355:28
at Scope.$eval (http://kibana.csp/bundles/commons.bundle.js:43583:29)
at Scope.$digest (http://kibana.csp/bundles/commons.bundle.js:43394:32)
at Scope.$apply (http://kibana.csp/bundles/commons.bundle.js:43691:25)
at done (http://kibana.csp/bundles/commons.bundle.js:38140:48)
at completeRequest (http://kibana.csp/bundles/commons.bundle.js:38338:8)

What version?

I was running 4.1, updated this AM to 4.4 and the issue went away.

Thanks