HTTP Error 500.30 – ANCM In-Process Start Failure

You’ve created a website or API using .NetCore and it all runs well locally. You deploy to an Azure App Service and it fails to start but the only error you see is that below.

HTTP Error 500.30 - ANCM In-Process Start Failure
Common causes of 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

You can use the Log stream page on the app service in Azure but you find that there is no meaningful error and Google throws up a few suggestions but none of them work… now what?

Well luckily there is a way to get a more meaningful error message, and that is by trying to run the app via the console in Azure Kudu:

  1. Navigate to the kudu pages of the site. You can do this via the Azure Portal or by simple adding “scm.” before the “azurewebsites.net” part of the url, e.g. “mysite.scm.azurewebsites.net”.
  2. Click on the Debug Console menu and choose Powershell.
  3. Navigate (or CD) to D:\home\site\wwwroot
  4. Type in dotnet NameOfYourSiteDLL, e.g. dotnet mysite.dll
  5. You should get a much more meaningful error message helping you resolve the issue – in my case I had forgotten to create the environment variables I needed.

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