IIS HTTP/2 headers only response with END_STREAM flag on headers

[JamesNK]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

A gRPC user is hosting their web app with IIS. They have noticed that a headers-only gRPC response (over HTTP/2) sends a HEADERS frame and an empty DATA frame with the END_STREAM flag. This goes against the gRPC HTTP/2 spec, which says the HEADERS frame should have the DATA frame.

Expected Behavior

IIS sends a HEADERS-only response with the END_STREAM flag in the HEADERS frame.

Note that this Kestrel has the correct behavior.

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

No response

Anything else?

No response

[ghost]

To learn more about what this message means, what to expect next, and how this issue will be handled you can read our Triage Process document.
We're moving this issue to the .NET 8 Planning milestone for future evaluation / consideration. Because it's not immediately obvious what is causing this behavior, we would like to keep this around to collect more feedback, which can later help us determine how to handle this. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact work.