Fiddler Ideas

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Can't run latest Fiddler because it failed to fully uninstall the previous version

The Fiddler 4 installer thinks there's something still installed in c:\Program Files (x86)\Fiddler2, but that folder no longer exists and the old version of Fiddler is no longer listed in "Programs and Features".

Error message when I run the new version:

"Machine-wide Progress Telerik Fiddler installation has been found at C:\Program Files (x86)\Fiddler2\ . Please, use that one or uninstall it before starting the per user Fiddler installation."

The offending folder does not now exist. "c:\Program Files (x86)\Entity Framework Tools" exists. "c:\Program Files (x86)\Google" exists. There is nothing between them. They are adjacent in the directory listing. 


  1. I uninstalled Fiddler 4.
  2. I installed Fiddler2 (installer file version from an old installer that, by luck, I happen not to have deleted. 
  3. I uninstalled Filddler2 manually.
  4. I installed Fiddler 4 again. 

Now Filddler 4 runs. 

But if I hadn't still had the old installer lingering in my downloads folder, I would have been out of luck. Please fix. 

  • Guest
  • Jun 6 2018
  • Under review
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