Thursday, August 27, 2015

Microsoft Message Analyzer and FiddlerCore

Microsoft Message Analyzer comes with a favorite scenario called "Pre-Encryption for HTTPS" scenario. The scenario relies on the FiddlerCore library. Due to a license issue, Microsoft does not ship the library with the analyzer. So when you try to use the scenario, you would encounter an error with the message below,

The Message Analyzer WebProxy provider depends on the FiddlerCore
library. The FiddlerCore library belongs to Telerik, Inc. and must be
installed separately. Please visit to download the
FiddlerCore installer and library from Telerik. A restart of Message
Analyzer is not necessary. 

Below is a screen capture.

To solve the issue, we simply download and install the FiddlerCore library, at present, from this URL.  The remaining issue is to determine where to install the FiddlerCore library. By default, FiddlerCore installer installs the library under the directory where the installer is. The directory would be a wrong directory for Microsoft Message Analayzer. To work with FiddlerCore, Microsoft Message Analyzer requires the FiddlerCore library to be installed under the directory of Microsoft Message Analyzer. If you install Microsoft Message Analyzer using its default installation directory, the FiddlerCore library's installation directory should be,

C:\Program Files\Microsoft Message Analyzer\FiddlerCoreAPI
If you are running 32-bit Windows or you installed 32-bit Microsoft Message Analyzer on its default installation directory, the directory to install the FiddlerCore library should be,

C:\Program Files (x86)\Microsoft Message Analyzer\FiddlerCoreAPI

Below is a captured FiddlerCore library installer screen shot that shows the correct installation directory is entered,

To configure and run a Pre-Encryption for HTTPS trace, see Microsoft Technet article Using the Network Tracing Features.


  1. If I install as directed, MS Message Analyser still cannot find it, and returns the same error message.

    1. This path C:\Program Files\Microsoft Message Analyzer\FiddlerCoreAPI is the one for most systems today. Did you use this one?

  2. I found with the latest version, I had to drop the FiddlerCore4.dll directly into C:\Program Files\Microsoft Message Analyzer\ (and I do have a 64-bit system).

  3. Still doesn't work for me. Getting:

    Fail to start live consumer
    Method not found: 'Void Fiddler.FiddlerApplication.Startup(Int32, Boolean, Boolean)'.

    Going to go back to Network Monitor.