How to Resolve: HTTP Error 500.0 — ANCM In-Process Handler Load Failure

When publishing an ASP.NET Core web application to Azure, some users may encounter this error:

“Error 500.0 — ANCM In-Process Handler Load Failure”

If you have an application that runs locally but fires this error when published to Azure, here are steps that should resolve this issue:

  1. If your application does not include a web.config file, add the following web.config file to the solution:

  1. If your application does not contain a “logs” folder and an “stdout.log” file, add a folder named “logs” to the wwwroot. Then, add a file named “stdout.log” to the logs folder.

  1. Ensure that the latest .NET version is installed. At the time of writing this article, .NET 8 is the latest version. Check the solution for any additional dependencies such as npm packages and frameworks.

  2. If the previous steps do not resolve the error, check the Application Event Logs and Web Service logs on the App Service for further clues.

Additional resources for troubleshooting:

ASP.NET Core OpenID Connect (OIDC) official Azure Sample: Tutorial — Enable your Web Apps to sign-in users and call APIs with the Microsoft identity platform for developers

Frustrated Stack Overflow users: How to fix error “ANCM In-Process Handler Load Failure”