IIS was not able to access the web.config file for the Web site or application

Error:

HTTP Error 500.30 – Internal Server Error

IIS was not able to access the web.config file for the Web site or application. This can occur if the NTFS permissions are set incorrectly. IIS was not able to process configuration for the Web site or application. The authenticated user does not have permission to use this DLL.

Cause:

Self Signed Certificate has expired.

Resolution:

1. Create a new self-signed certificate from DEV server.
2. Generate a pfx private key certificate from DEV server.
3. Upload pfx private key certificate to SSL of your App Service.
4. Get “Thumbprint” of private key certificate you just uploaded to Azure App Service.
5. Go to Configuration of Azure App Service and update the
   WEBSITE_LOAD_CERTIFICATES.
6. Update your app’s appsettings.json file.
7. Redeploy app.

Using a Self-Signed Certificate for IdentityServer4 in Azure App Service