Fiddler Classic freezes when I try to enable 'decrypt HTTPS traffic'.

[logonzal]

Hi All,

I am having an issue where I am not able to enable "decrypt HTTPS traffic' in Fiddler Classic. It freezes and does nothing until I end the task using task manager. I tried this on 4 different workstations and same issue. Let's focus on one. It is running Windows 10 Pro 20H2 build 19042.1237. Please let me know if they are any logs I can collect/review to try and determine what is causing the issue. Thanks!

[Nick Iliev]

Try to reset your root trust certificates and make sure that you have the administrative rights to install/trust certificates and to change the OS proxy settings.

[Bru]

Same problem , have tried running in admin, as well as renewing cert. If left long enough, it might give the pop up to allow the cert to be installed, only to then be blocked in the browser for all traffic. Turning of Capture then frees it up. 

experianced this on
win10 20H2 build 19042.1237
win11 21H2 pro build 22000.194 

[Nick Iliev]

Hi Bru Gund,

 

We are trying to reproduce the issue on our side, but until its moment, to no avail. The Fiddler Classic works as expected on clean Windows 11 installation, and we are also not seeing any issue on Windows 10 with update KB5005611.

Could you please try to update your OS to https://support.microsoft.com/en-us/topic/september-30-2021-kb5005611-os-builds-19041-1266-19042-1266-and-19043-1266-preview-a37f5409-f320-4175-9a66-c2682fc11c07

After the update, reset your trust certificates (Tools > Options > HTTPS . Actions > Reset All Certificates) and then try to re-enable to the Decrypt HTTPS traffic option.

[Bru]

attempting to reset the cert works fine, when attempting to renew cert results in a frozen/nonresponsive fiddler program
i had attempted to install the KB5005611  through the update, thought it had. however it is not currently showing.sin
Hotfix(s):                 5 Hotfix(s) Installed.
                           [01]: KB5005539
                           [02]: KB4562830
                           [03]: KB4570334
                           [04]: KB5005565
                           [05]: KB5005699

if it ever renews the cert, then when capturing, it will either stop all traffic to all browsers, or only effect Edge Version 94.0.992.38 (Official build) (64-bit)
current chrome Version 94.0.4606.81 (Official Build) (64-bit)

dump from task manager attached if that helps. 

[Nick Iliev]

Hey Bru Gund,

 

When using the renew certificate action, the OS prompt is often displayed in the background, and at that time, the Fiddler Classic UI might be blocked from further interaction. Could you verify that you are seeing and accepting the certificate installation explicitly through the OS prompt?