Discover: unknown error, SearchError: unknown error

Hi,

Kibana is throwing this error for all queries:

SearchError: unknown error
    at http://my-dev-elk:5601/bundles/kibana.bundle.js:2:520531
    at processQueue (http://my-dev-elk:5601/built_assets/dlls/vendors.bundle.dll.js:293:199687)
    at http://my-dev-elk:5601/built_assets/dlls/vendors.bundle.dll.js:293:200650
    at Scope.$digest (http://my-dev-elk:5601/built_assets/dlls/vendors.bundle.dll.js:293:210412)
    at Scope.$apply (http://my-dev-elk:5601/built_assets/dlls/vendors.bundle.dll.js:293:213219)
    at done (http://my-dev-elk:5601/built_assets/dlls/vendors.bundle.dll.js:293:132717)
    at completeRequest (http://my-dev-elk:5601/built_assets/dlls/vendors.bundle.dll.js:293:136329)
    at XMLHttpRequest.requestError (http://my-dev-elk:5601/built_assets/dlls/vendors.bundle.dll.js:293:135346)

It is my dev instance which i use for testing. So it is not heavily loaded.

There are no errors in elasticsearch logs. In browser dev tools i get this error repeatedly:

Failed to load resource: net::ERR_CONNECTION_TIMED_OUT

Deleting .kibana index didn't fix the issue.

Kibana logs have this:

{"type":"response","@timestamp":"2019-08-13T09:03:41Z","tags":[],"pid":1,"method":"get","statusCode":304,"req":{"url":"/built_assets/css/plugins/console/index.light.css","method":"get","headers":{"host":"my-dev-elk:5601","connection":"keep-alive","user-agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.142 Safari/537.36","accept":"text/css,*/*;q=0.1","referer":"http://my-dev-elk:5601/app/kibana","accept-encoding":"gzip, deflate","accept-language":"en-GB,en;q=0.9,en-US;q=0.8,kn;q=0.7","if-none-match":"\"92fe860098ef8b025e3578b38fbb0ffc82309dcd-/-gzip\""},"remoteAddress":"10.76.81.65","userAgent":"10.76.81.65","referer":"http://my-dev-elk:5601/app/kibana"},"res":{"statusCode":304,"responseTime":5,"contentLength":9},"message":"GET /built_assets/css/plugins/console/index.light.css 304 5ms - 9.0B"}

Thanks,

The queries on other index pattern get's executed properly though. Only difference between the both is the failing queries were made on index which has some nested fields. (Although i don't know how is it related). I query on the index with nested fields immediately after introducing nested fields (ie less data) but after the data has grown overnight i started getting above described error when i try to query that index (size has now grown to 2.6G, i don't think this is the cause either)

I can't think of how nested fields could cause this because if there was some error, i was expecting them in elasticsearch. but elasticsearch log doesn't throw any error

Am I understanding correctly that Kibana loads just fine, but when you attempt a search, you get that error? Or is Kibana failing to load completely?

Are there any other logs on the Kibana server?

Yes, kibana loads properly but attempt to search throws that error. I have pasted the kibana log in my first post.