In this post, we will look at the error “Backend service URL is not defined” when making a request to an ASP.NET Web API through API Management.
I have a .NET Core Web Api with Swashbuckle / Swagger. The Web Api is published to an Azure App Service, and an Azure API Management has this API loaded.
We can run a test message using the APIM:
We get a 500 Internal Server Error:
To examine the response, click on Trace and Backend:
We see the message “Backend service URL is not defined”:
To resolve this, in APIM go to the App Service. Under Settings, in the Web Service URL field, enter the URL of the app service:
Now when you run this, you will get a 200 response back: