When we publish an ASP.NET Core application in an Azure App Service, and it has an error that does not allow it to load, we are usually presented with an error screen like the following when trying to enter to the App:

HTTP Error 500.30 – ANCM In-Process Start Failure

Common solutions to this issue:

• The application failed to start
• The application started but then stopped
• The application started but threw an exception during startup

Troubleshooting steps:

• Check the system event log for error messages
• Enable logging the application process’ stdout messages
• Attach a debugger to the application process and inspect

For more information visit: https://go.microsoft.com/fwlink/?LinkID=2028265

This is a generic error, so it tells us nothing more than “there was an error.” How can we get more information about the error? Since the app doesn’t even load, logging is not an option.

Fortunately, Azure offers us a console through which we can execute commands. We can run the application through this console and thus visualize the real error that is causing our application not to load.

In the Azure App Service, go to the Console menu:

Here we are presented with a console, and in it we can run our application. For that we put the name of our project followed by “.exe” and press the Enter key. For example, my project is called “PWADemoTest.Server”, so in the console I must put PWADemoTest.Server.exe:

In this way I get the indicated error. In my case, I have not specified the IdentityServer4 Key. With this information I can work to solve my situation.

Courses

Get to the next level in ASP.NET Core with my courses:

Programming in Blazor: Build an application with Blazor, so that you too can have an interactive Web Application that uses C# on the browser

Building RESTful Web APIs with ASP.NET Core: Learn techniques in building Web APIs with the latest version of ASP.NET Core

Regards!