Could Fiddler interfer with VSO?

2 posts, 0 answers
  1. Rod
    Rod avatar
    15 posts
    Member since:
    Jun 2011

    Posted 25 Oct 2015 Link to this post

    Tonight I was doing some development on a ASP.NET Web Forms app I'm writing at home. It was causing some problems and I wanted to see the HTTP traffic so I brought up Fiddler2 to give it a try. But the instant it came up it complained about something that it thinks I need to do on my Windows 10 machine. I don't know nor understand what it is, and since I was running out of time and needed to get on with other things, I closed the dialog box, did some more work on the app and tried to check it into to my repository on Visual Studio Online (VSO).

    That's when things started to go badly for me. I couldn't check anything into VSO. VSO thought I wasn't event connected to it. It gave me an access error, something like "TF30063 Access denied". Now I'm trying to shut down my machine to go to bed, and I discovered that Fiddler was still up and running. I wasn't even aware that it was still up.

    So my question is this, does Fiddler2 interfere with VSO? It certainly looks like it might, as I think this is more than just a coincidence that I was having this problem, I've never had this problem in the months that I've been using VSO and Fiddler2 was running in the background.

  2. Eric Lawrence
    Eric Lawrence avatar
    832 posts

    Posted 26 Oct 2015 Link to this post

    Hi, Rod--

    Unfortunately, there's not enough information here to go on. 

    Can a proxy interfere with network traffic? Sure. 

    " I don't know nor understand what it is"

    The message explained that Windows 8+ "Metro" apps and the Edge browser use a technology called "AppContainer" which usually must be configured to allow requests to go through Fiddler. Configuration consists of clicking "Allow all" and "Save" in the tool that it offers to launch. Notably, Visual Studio does not use AppContainer.

    With regard to your VSO problem, it would be helpful to understand what, if any, rules you have configured in Fiddler, and whether you've configured Fiddler to decrypt HTTPS traffic, and if so, whether you've configured Windows to trust Fiddler's root certificate. Sending a traffic capture (File > Save > All Sessions) to us (Help > Send Feedback) would help reveal the nature of any problems you've encountered.

    Eric Lawrence
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