Introduction

Fiddler version 2.1 introduced some much-needed (but breaking) architectural changes to the Fiddler API set.  This means that extensions written for versions of Fiddler prior to version 2.1 will need minor updates in order to run inside Fiddler version 2.1 and later.

What updates are needed for all extensions?

In order for Fiddler to load an assembly .DLL file containing an extension, the assembly must have the new Fiddler.RequiredVersion attribute set.  This attribute specifies the minimum version of Fiddler required to use your extension.  It is defined inside the Fiddler.exe assembly, so be sure that you have Fiddler.exe in your project's References and Fiddler in your using clause.

• Add using Fiddler; to top of AssemblyInfo.cs
• Add [assembly: Fiddler.RequiredVersion("2.1.0.1")] to your AssemblyInfo.cs file

What updates are needed for Inspector objects?

1. Install Fiddler v2.1 or later
2. Remove the project's reference to plugins.dll
3. Add a reference to Fiddler.exe
4. Update instances of Inspector to Inspector2
5. Update instances of IRequestInspector to IRequestInspector2
6. Update instances of IResponseInspector to IResponseInspector2
7. Remove implementations of the Announce method.
8. Add using Fiddler; to top of your .CS files that contain classes that implement the IRequestInspector and IResponseInspector interfaces
9. Add the Fiddler.RequiredVersion attribute, as specified above.

What updates are needed for AutoFiddler objects?

The IAutoFiddle interface was replaced with IAutoTamper.

1. Install Fiddler v2.1 or later
2. Remove the project's reference to plugins.dll
3. Add a reference to Fiddler.exe
4. Update instances of IAutoFiddle to IAutoTamper.
5. Implement an OnLoad handler
6. Remove the GetRank handler
7. Add using Fiddler; to top of your .CS files that contain classes that implement the IAutoTamper interface
8. Add the Fiddler.RequiredVersion attribute, as specified above.

Where can I find more information?

See Extending Fiddler with .NET Code.