502 proxy error calling Zeppelin paragraph (Impala query) via REST API (fine when run via Zeppelin UI)

[#1]

I'm calling an Impala query paragraph in a Zeppelin note, using the REST API (so I can parse the returned data in Javascript) and it works fine some of the time, and other times it fails with a 502 proxy error. The same paragraph run via the Zeppelin UI always works fine.

I'm running it synchronously as per: https://zeppelin.apache.org/docs/0.8.2/usage/rest_api/notebook.html#run-a-paragraph-synchronously

How would I go about fault finding on this please? I'm unsure where to start.

Or, is there another way I can access the data, it looks to me like the asynchronous method will not return any data, just a status?

https://zeppelin.apache.org/docs/0.8.2/usage/rest_api/notebook.html#run-a-paragraph-asynchronously

[#2]

@ajck  Can you share the stack trace of the error

[#3]

@ajck, have you found a solution for your issue? If you have, can you please post the appropriate solution here? If you are still experiencing the issue, can you provide the information @Scharan has requested?