Hi,
NGINX is returning an HTTP 502 when the Upstream Header Name contains whitespace. The following error message is recording in the error log.
upstream sent invalid header: "IIS\x20..." while reading response header from upstream

The request is returned successfully from the Upstream Server with the headers listed below.
Cache-Control:
Content-Length:
Content-Type:
Server:
X-AspNet-Version:
Set-Cookie:
X-Powered-By:
IIS SERVER:
Date:

I suspect "IIS SERVER:" header is the culprit. Would anyone know how to Ignore or correct the problem? Apologies is this is duplicate but I've not been able to find a resolution.