ERR_SPDY_PROTOCOL_ERROR Ajax .net web api

Question

Running into a very strange error when trying to execute Ajax calls to a .NET Web Api hosted on IIS on Azure.

I've got my SSL cert from let's encrypt, it's applied to the website properly. When I try to execute an ajax call I get:

net::ERR_SPDY_PROTOCOL_ERROR

If Fiddler is open, all works properly. With Fiddler closed, we get the error. Regular old HTTP works just fine.

Answer 1

For me the issue was that I was sending an empty Authorization header.

The login to my app (an AngularJS SPA) sends a username/password in a JSON object, and if the login is valid then a JWT is returned which is then used for the Authorization header - e.g. Bearer {JWT} for future API requests.

Not sending an Authorization header when there was nothing to send fixed the issue.