The “HTTP Error 500.30 – ASP.NET Core app failed to start” error typically occurs when there is an issue with the hosting configuration or the runtime environment of your ASP.NET Core application. Here are a few potential solutions to resolve this error:

1. Check the hosting configuration: Ensure that the hosting configuration for your ASP.NET Core application is properly set up. This includes verifying the web.config or appsettings.json files for any errors or misconfigurations.
2. Verify the .NET Core runtime: Make sure that the correct version of the .NET Core runtime is installed on the server and that it matches the runtime specified in your application’s configuration. You may need to install or update the runtime if it is missing or outdated.
3. Restart the application: Try restarting the application to refresh the runtime environment. This can help resolve any temporary issues that may be causing the application to fail on startup.
4. Check for missing dependencies: Ensure that all the required dependencies and libraries are present and properly referenced in your ASP.NET Core application. Missing or incompatible dependencies can prevent the application from starting successfully.
5. Review server logs: Examine the server logs for more detailed error messages or stack traces. They can provide insights into the root cause of the issue and help you identify any specific configuration problems or missing components.