Undici error on Windows with https

[ibenrh]

When running func start with --useHttps on Windows you get the error message:

Exception: Headers.append: ":method" is an invalid header name.
Stack: TypeError: Headers.append: ":method" is an invalid header name.

This is caused by any undici versions higher than 5.27.2.

Example at: https://github.com/pellebjerkestrand/azure-functions-core-tools-invalid-header-method/tree/main

[ejizba]

Looks like we're not the only ones hitting an error like this. It has to do with pseudo headers in http/2 and I'm not entirely sure what the recommended behavior is.

I can repro this myself on Windows with --useHttps, but not mac. I checked telemetry and I'm not seeing evidence of this error in Azure - seems like it's only a problem locally.

[steffennilsen]

I am running into the same issue with local hosting on Linux after enabling --useHttps, @ibenrh solution of downgrading undici solved the issue for me

[ibenrh]

Yeah, we've temporarily solved it that way too for now, @steffennilsen :)

[timtucker-dte]

Would starting up the local server with http2 support disabled fix this by preventing the browser from sending http2 pseudo headers?

[timtucker-dte]

Anyone else tested this recently?

Tried again with 4.6.1 / undici 5.28.5 today and https seems to be working.