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I have Windows 8.1 installed on my computer and regularly use Fiddler to capture web traffic.

Recently, however, when I open Fiddler and it strats to capture web traffic, my Internet connectivity dies.

The error I get when I open IE is "the proxy server isn't responding."

In Chrome, I get "Could not connect to proxy server" with the following error: "Error code: ERR_PROXY_CONNECTION_FAILED."

Fiddler doesn't even capture any of the requests going out. The weird thing is that Fiddler was working ok just some days ago and nothing was recently installed on my system.

Searching the Internet for 5 hours, trying everything, and no effective response.

This also had no effect: http://www.telerik.com/blogs/fiddler-and-internet-explorer-11-on-windows-8-1​

It seems that the proxy server created by Fiddler is simply not attending to any traffic.

If I close Fiddler or disable the capture mode my internet come back to normal.

Uninstall and reinstall Fiddler does not solve the problem, neither restart Windows.​

This question has some similarities with my problem, but as I said, none of the answers worked for me.

Why is Fiddler having this problem, and how can I fix it?

Community
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Luis
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1 Answers1

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99% of the time, this is caused by running a 3rd-party firewall which is blocking access to Fiddler.

1% of the time, this is caused by plugging a Windows Phone device into your PC over USB. The Windows Phone team steals Fiddler's default port (8888) from it.

Running Help > Troubleshoot and updating your question with its output may help.

EricLaw
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