Fiddler Proxy Settings have corrupted Visual Studio networking

[Shiv]

Hello,

I recently installed Fiddler on my Windows 10 Machine to trace the networking requests of my ASP.Net application.
I enabled HTTPS decryption and allowed trusted certs as prompted.

 

The problem - 

It worked fine, however, Visual studio is now unable to access the internet. More specifically, I get this error [nuget.org] Unable to load the service index for source https://api.nuget.org/v3/index.json.
  The ServicePointManager does not support proxies with the https scheme.
I have tried all of the solutions posted here - https://github.com/NuGet/Home/issues/2880 and here - https://github.com/NuGet/Home/issues/5358

This is not a Visual Studio issue because it has only started to happen when I installed Fiddler.
I have spent about 3 days trying to resolve it.I have tried to undo all of the Fiddler settings, uninstalling it, even uninstalled and installed Visual Studio.
In some random patterns, when I open VS and open Fiddler then I try to restore packages it will work, but only if I open Fiddler. This however does not work majority of the time.

[Eric R | Senior Technical Support Engineer]

Hi Shiv,

Thank you for providing the error message. This appears to be happening because of the configuration of the ServicePointManager in Visual Studio. A ServicePointManager sample implementation can also be found on the ServicePoint API documentation. Let me provide a few different options for troubleshooting below. 

If the goal is to continue using Visual Studio with Fiddler, I recommend either disabling restore on build or disabling it completely using the Options Menu as shown in the below screenshot. 

An additional area of troubleshooting is removing the intermediate certificates which can be removed directly from within Fiddler Options menu. See the below screenshot.

Lastly, I recommend verifying the Proxy Settings are not configured when Fiddler is Running. See the below screenshots for the proxy settings that are not configured.

Please give these options a try and let me know the results. Thank you and I look forward to your reply.

Regards,

Eric R | Senior Technical Support Engineer
Progress Telerik

[Shiv]

Hi Eric,

 

Thank you very much for your response.
I did ensure that the proxy settings were off, and I have already tried removing the certificates from Fiddler. Unfortunately, those options did not work.

I don't mind removing fiddler all together as I don't need it running side by side right now. What's more important is for my Dev environment to be restored to a state where I can work with Nuget consistently again.

Thanks in advance.

[Eric R | Senior Technical Support Engineer]

Hi Shiv,

This is completely understandable. Although, rarely does uninstalling Fiddler break internet access for other programs. In order to troubleshoot this further, I will need the following information. 

1. What is the version of Fiddler?

2. What OS and version is in use?

3. Can you try uninstalling Fiddler by executing %LOCALAPPDATA%\Programs\Fiddler\uninsta.exe?

4. After uninstalling Fiddler is NuGet available through a browser?

5. What security software is in use? 

6. Is a VPN in use?

7. Are you able to provide a screenshot of the VPN settings?

8. Any other additional information like errors or screenshots that you may find helpful in this case.

Once I have the above information, I will be able to troubleshoot further. 

In the meantime, please let me know if you have any additional questions. Thank you.

Regards,

Eric R | Senior Technical Support Engineer
Progress Telerik

[Shiv]

 

1. What is the version of Fiddler?

v5.0.20194.41348 for .NET 4.6.1

 

2. What OS and version is in use?

Windows 10 Enterprise

3. Can you try uninstalling Fiddler by executing %LOCALAPPDATA%\Programs\Fiddler\uninsta.exe?

 

4. After uninstalling Fiddler is NuGet available through a browser?

I can usually access https://api.nuget.org/v3/index.json through the browser with, or without Fidler.

5. What security software is in use? 

Just Microsoft Defender, Have tried turning firewalls on and off.

6. Is a VPN in use?

No

 

 

[Shiv]

See screenshot - This message has also popped up sometimes.
Basically if I open Fiddler, Microsoft Outlook also stops working (Stops sending and receiving emails).

[Eric R | Senior Technical Support Engineer]

Hi Shiv,

Thank you for providing the requested information and screenshots. Although, if Fiddler is uninstalled and you are able to access the internet, this probably means that the issue is not caused by Fiddler and is likely some other configuration. Below are a few areas for troubleshooting.

1. For Visual Studio (VS), one area to investigate is the devenv configuration. Can you verify if the devenv.exe.config file is not pointing to the Fiddler Proxy? If it is and Fiddler is uninstalled, this element will need to be removed. See the StackOverflow question for more details. 

2. Additionally, you may need to confirm that no other plugins/extensions are installed with Visual Studio that are related to Fiddler.

3. The machine.config might also cause the VS error. Can you verify Machine Config is not pointing to the Fiddler Proxy? See the Capturing Traffic from .NET Services with Fiddler blog post for more details.

4. The Fiddler Startup error is also a concern as this might also be the cause. Do you know if Fiddler is being ran as a Service, in the command line or by some other process? I recommend opening up Task Manager and stopping all Fiddler.exe instances. See the below screenshot for more information.

In the meantime, please let me know if you have any additional questions. Thank you and I look forward to your reply.

Regards,

Eric R | Senior Technical Support Engineer
Progress Telerik

[SK]

editing machine.config after uninstalling fiddler solved my problem