Edge browser does not connect to Fiddler proxy

[Aril]

Dear all expert users,

I work with a web app having a specific issue working with Edge browsers. To inspect what happens, I wanted to monitor and debug with Fiddler, but I just can't make my Edge browser communicate with Fiddler2. My environment looks like this:

* Microsoft Edge 38.14393.0.0; proxy settings: Automatic
* Windows 10
* Fiddler v4.6.3.44034
* disabled Windows Firewall.

(1) Browsing in Edge with Fiddler off:
I can surf about as desired.

When I now inspect Edge proxy settings, they are set not to use a proxy. This is as expected.

(2) Starting Fiddler and trying again:

Any attempts to load a web page makes Edge complain, it can not connect to the proxy server (Fiddler). 

This time, Edge proxy settings were changed after Edge restart. Now it's set to use 127.0.0.1:8888 for HTTP and HTTPS, as expected. 

If I try opening another browser session from Fiddler, IE works well and Chrome works well. Only Edge does not connect to the proxy..

 

I read other threads on this forum, and found suggestions this might happen because of windows firewall, possibly even some hard coded matter in the firewall. However, as I stated above: My problem persist even with firewall turned on or off. Therefore my conclusion: Edge and Fiddler don't cooperate, and it has not to do with the firewall settings.

Uless of course, anyone is able to explain to me what happens or how to make things work. (It would typically be some simple setting I have got wrong, for sure.. You'd make me really happy, if you made me understand. :-)

 

Cheers,

Aril

[Tsviatko Yovtchev]

Hi,

Have you tried the EnableLoopback utility? Normally Edge won't be able to connect to localhost (i.e. 127.0.0.1) and that's how you can configure it to do so. 

Regards,
Tsviatko Yovtchev
Telerik by Progress

[Elliott]

Fiddler > Tools > Win8 Loopback Exemptions > check Microsoft Edge

That does it.

[Ed]

I'm running Windows 11, Fiddler as admin.  Loopback extension is checked, but still no traffic showing up.  Google traffic works just fine.

[Nick Iliev]

Hey Ed,

 

While ago in the days of Windows 8, the loopback exemptions were solving some problems with applications that were not respecting the system proxy. That is no longer the case with Windows10 and Windows `11, so it is likely that your issue is not related to the one discussed above. You could try the following:

- Explicitly add the new SSL protocols in Fiddler (Tools > Options > HTTPS > Protocols) and add TSL1.2. For example, add the following:

 <client>;ssl3;tls1.0;tls1.2

- From the same menu (Tools > Options > HTTPS), turn on the option "Ignore server certificate errors (unsafe)"

- Completely reset the root trust certificate (Tools > Options > HTTPS > Actions)

- Download the Bouncy Castle certificate generator (CertMaker from here) and make it the default certificate generator in Fiddler (as described here)