FiddlerCore not registering as a proxy when running FiddlerApplicaiton with .RegisterAsSystemProxy()

[Tomasz]

Hello, i have app using fiddler, and i have problem like in Subject. Proxy in windows settings turn on like normal but i can't see result of fiddler proxy. Im using windows 11. There's any way to fix that? Thanks! :) 

[Nick Iliev]

Hello Tomasz,

 

There might be multiple reasons for not seeing the expected result - from misconfiguration of the FIddlerCore to not seeing specific application traffic due to the application not respecting the operating system proxy settings.

The easiest way to check if your FiddlerCore is configured properly is to run it and then try to capture traffic from an application guaranteed to respect the system proxy settings. Another option to verify that FiddlerCore is working as expected is to make an explicit request to its proxy address - this will help you in identifying if you have a FIddlerCore configuration issue or a more profound system issue (e.g., something related to security policies that are preventing the Fiddler proxy from working as expected).

More information about configuring FiddlerCore can be found here: https://docs.telerik.com/fiddlercore/basic-usage/register-as-system-proxy 

Ensure that FiddlerCore is configured to capture HTTPS through the instructions provided here: https://docs.telerik.com/fiddlercore/basic-usage/capture-https-traffic 

 

Regards,
Nick Iliev
Progress Telerik