I have implemented IdentityServer4 on an asp.net core 3.1 webapp I uploaded to an Azure App Service which is being consumed by an Angular 9 (using oidc-client 1.10.1) on another Azure App Service. When running these two on my local IIS 10.0 Web Server, everything works fine. On Azure, when calling UserManager.signinRedirect() in the the Angular 9 app, it responds the following error (I can see on the browser console):  

`Error: Uncaught (in promise): Error: Invalid response Content-Type: text/html, from URL: idpservername.azurewebsites.net/.well-known/openid-configuration`  

If I copy/paste the URL on the address bar of the browser it responds a valid json content.  

I googled and found this link:
`<https://github.com/IdentityServer/IdentityServer4/issues/2967>`
But it does not help much because the case is closed due to lack of activity where last answer reads **"it turns out that IIS was not rendering html properly.** I am running the IdentityServer on an App Service (I am not using a Virtual Machine), therefore, I don't have access to the IIS (if the answer implies configuring something directly on the IIS Web Server).  

Do you have any suggestions on how to solve this problem? :-\