Hello Patrick,
Do you mean that the check box for starting as system proxy is unchecked, as I just checked the code and it seems we are not disabling it (it should become grayed out in this case) anywhere?
Otherwise, we investigated the call stack again, and the method that's failing is InternetSetOption in wininet.dll. What's happening behind the scenes:
Fiddler - Extensions. This page contains useful extensions for Fiddler. For best results, please ensure that you're running the latest version of Fiddler2. You can develop your own extensions using the IFiddlerExtension interface. Syntax-Highlighting Addons. Tip: If you are a Web Developer, you need the Syntax-Highlighting extensions! Fiddler Web Debugger Tool. The Fiddler tool helps you debug web applications by capturing network traffic between the Internet and test computers. The tool enables you to inspect incoming and outgoing data to monitor and modify requests and responses before the browser receives them. Fiddler also includes a powerful event-based scripting subsystem, which you can extend by using any.NET. Add Reference to Fiddler Start Visual Studio 2005 or later. Create a new Project of type Visual C# Class Library. Right-click the project's References folder in the Solution Explorer. Click the Browse tab and select Fiddler.exe in the C: Program Files Fiddler2 folder. Click Ok to add the reference.
- on startup, Fiddler is getting the network connections for the OS, and replaces their proxy settings with the ones pointing to the port it's listening onto (127.0.0.1:8888 by default). It seems the 'replace step' is the one that fails
- on exit, Fiddler is restoring the previous settings proxy settings.
That said, probably there are some obscure network connections (or proxy settings for these connections), which are breaking the Win32 call we are making. Could you check whether you have some 'strange' or non-trivial network connections, or whether you use some proxy by default (e.g. some corporate proxy)?
Also, something that could probably help is to enable DebugSpew mode (by adding the DebugSpew regkey), in which Fiddler logs messages to the debug output. These messages can be monitored using DebugView for example.
Fiddler Internet Explorer Add On
I also did a quick research, but it seems the error is not so common case - anyway I am posting it here in case you recognize some of the scenario mentioned, e.g. the Error Message: Proxy Reports: 87 The parameter Is Incorrect one.
Fiddler Addons
Regards,
Boby
Progress Telerik