502 and 494 Error : The request could not be satisfied by cloudfront

I am getting this error from cloudfront when I am sending big GET request to my application :

494 Error : The request could not be satisfied. Bad request. We can't connect to the server for this app or website at this time.

I know that cloudfront has a limit of around 10k characters and when violated it responds with 413 error but I am not understanding why cloudfront throws 494 and what does it actually means.

On that note, Sometime I am seeing 502 error when sending big GET request to my application :

502 Error : The request could not be satisfied by cloudfront. Cloud front couldn't connect to the origin or origin returned an incorrect response.

Would any one know the meaning of these errors ( as these docs define error connecting to origin but why only with big request ) and how to fix them.

Note: I don't have the logs from cloudfront as it doesn't log big request.