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WebAPI 2.6 Debugging WebAPI using Fiddler and F12

Since the WebAPI is usually invisible and doesn't have a real output-page it’s a bit harder to debug. What makes things even more difficult is the fact that DNN doesn't log WebAPI errors (it should, but that's a pending issue). So I'll show you the most important tools to help you get started.


  • I would recommend to watch the Basic-Series Parts 1.1, 1.2 and 1.3 since it explains the very basics of WebAPI.
  • Since this is part 2.2, you would also benefit from starting with 2.1, 2.2, 2.3, 2.4 and 2.5.
  • Even if you don't, make sure you have a working DNN with 2sxc 6.4 installed ( see this blog for help).
  • The App you'll install can be found in the App-Catalog - direct link here

In the following 16 minute Video, I'll show you

  1. Understanding where Issues can occur (what layers)
  2. Get to know your most important tools Fiddler and Browser-Debug
  3. Use Console.log()
  4. Understand how the JavaScript can go wrong...
  5. ...or the server
  6. Learn to understand server error numbers like 400 or 500 to corner your problems

Let's go!

Further links

With love from Switzerland,

Daniel Mettler grew up in the jungles of Indonesia and is founder and CEO of 2sic internet solutions in Switzerland and Liechtenstein, an 20-head web specialist with over 800 DNN projects since 1999. He is also chief architect of 2sxc (see github), an open source module for creating attractive content and DNN Apps.

Read more posts by Daniel Mettler