Hi there, this sounds related to Kibana 5.1.2/ES 5.1.2 - Index patterns with more than 1000 fields. From that post:
The 413 (PAYLOAD TOO LARGE) response is actually most likely coming from Elasticsearch. Kibana is just surfacing the error it gets back.
It happens as part of a request Kibana is making to it, so it would be useful to see what that request looks like. If you open your browser's debugger, you can check the request in the network request. That might indicate why that request is so large... most likely it's related to the field count, but I couldn't tell you offhand why field count would be making a request to large.
Could you check the network requests that get logged when you refresh the field list and tell me what you see there?
And could you tell me which version of the Elastic Stack you're using?
Thanks,
CJ