HttpContext is NULL when running web app in IIS

Question

I have two application, both running on the same Windows machine. One application is IdentityServer4, and the other is my own web application (Server side Blazor app).

Answer 1

If the HttpContext null-reference exception happens after deployment to Azure App Services or IIS, you might have forgotten to enable WebSockets.

Here is the deal:

If the app runs on Windows with IIS: WebSockets must be enabled.

See the IIS/IIS Express support section.

It seems that this is a prerequisite that you have to follow. I only recently discovered this myself after dealing with the same issue and deciding to publish my app to Azure from within Visual Studio. After I did so, Visual Studio gave me a nice warning telling me to enable WebSockets protocol on the Azure App Service.