Custom Inspector Never Appears

4 posts, 0 answers
  1. Jesse
    Jesse avatar
    2 posts
    Member since:
    Apr 2015

    Posted 18 Apr 2015 Link to this post

    I'm trying to write a response inspector, and after trying numerous things, I can't get it to appear on the Inspectors tab.

    I've tried this basic test, and it doesn't seem to get loaded into Fiddler:

    using System.Windows.Forms;
    using Fiddler;
    [assembly: RequiredVersion("")]
    namespace Test
        public class TestInspector : Inspector2, IResponseInspector2
            public override void AddToTab(TabPage o)
                o.Text = "TestInspector";
            public override int GetOrder()
                return 0;
            public void Clear()
            { }
            public byte[] body { get; set; }
            public bool bDirty { get; private set; }
            public bool bReadOnly { get; set; }
            public HTTPResponseHeaders headers { get; set; }

    I've compiled this against Fiddler and, and tried loading it into both. Neither seems to work.

    I know that my dll is being loaded by Fiddler though. If I add this to the DLL, my Message Box appears while the application is loading.

    public class TestExtention : IFiddlerExtension
        public void OnLoad()
            MessageBox.Show("Hello Fiddler!");
        public void OnBeforeUnload()

    I've even tried compiling / loading inspectors I've found on codeplex, but none of them seem to work.

    Any help would be greatly appreciated.

  2. Eric Lawrence
    Eric Lawrence avatar
    832 posts

    Posted 20 Apr 2015 Link to this post

    Hello, Jesse--

    Based on the behavior you describe, the most likely explanation is that your assembly isn't placed in the correct folder. It needs to be in the Inspectors folder (from which Inspectors are loaded), not the Scripts folder (where IFiddlerExtensions are loaded).

    When building Inspectors or extensions, you should type the following in the QuickExec box below the Web Sessions list:

       prefs set fiddler.debug.extensions.showerrors True

    And hit enter, then type

       prefs set fiddler.debug.extensions.verbose True

    Hit enter, and restart Fiddler.

    Subsequently, Fiddler's LOG tab will show much more information about the loading of Inspectors and other extensions. 

    Tip: You should also bump your RequiredVersion to or ideally unless you really plan on testing it against the ancient and unsupported v2.3.

    All the best,
    Eric Lawrence

    See What's Next in App Development. Register for TelerikNEXT.

  3. corey
    corey avatar
    1 posts
    Member since:
    Apr 2018

    Posted 30 Apr 2018 in reply to Eric Lawrence Link to this post

    I suffer the same problem and I am sure that the .dll file is placed in the Inspectors folder. But nothing happened in fiddler, no error and no page. I do not know what happen and how to fix it.
  4. Alexander
    Alexander avatar
    383 posts

    Posted 14 May 2018 Link to this post


    Have you checked the official documentation about writing custom inspectors - link?

    Progress Telerik
    Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Feedback Portal and vote to affect the priority of the items
Back to Top