I can access every other file in this folder from IIS (10) as static content, except for the .gltf file which returns the 404 page.
I have added MIME mapping to IIS everywhere at this point (web.config for the ASP.NET Core 2.2 site, top level of IIS, site level of IIS). It is model/gltf+json. I tried application/json and application/octet-stream just in case. It returns 404 in all situations.
I tried allowing the server to serve all static files with a wildcard MIME mapping. Even this fails.
If I rename the .gltf file to .json, it works fine.
I tried FailedRequestTracing, which provided me with a huge xml file. Going through that revealed nothing enlightening to me, but maybe I just don't know enough about inner workings of IIS.
Same trouble on IISExpress (ran from Visual Studio 2019).
I tried converting .gltf to .glb using https://glb-packer.glitch.me/ but .glb extension exhibits the same issue with IIS -> 404.
Restarting IIS with
iisreset /restart didn't help.
I am not using any URL rewrite rules.
Adding the option
ServeUnknownFileTypes = true to StaticFiles middleware made no difference.
Have you encountered a problem like this before? Any suggestions as to what to try next?
UPDATE: I have managed to narrow down the problem to AspNetCoreModuleV2 handler. When not present, .gltf file is served correctly. Now, I do need this module to run, so that's a problem.
UPDATE: figured it out finally... I'll post an answer for the next unfortunate soul to stumble upon this.