Hey everyone,

I’m hitting a bit of a wall with mTLS in Fiddler Everywhere. My logs are showing the following error repeatedly: "[Error] [Fiddler] The server [domain] requested a client certificate, but no client certificate was available."

The Situation:

• I have my client certificate ready (as a .pfx, no password).

• My setup involves several subdomains, specifically:

  • appdata.mydomain.com

  • apps-boost-global.mydomain.com

• They all use the SAME certificate.

The Problem: I can’t find a clear, definitive path on where to save these files so Fiddler Everywhere actually "sees" and picks them up. I've seen mentions of Documents\FiddlerCore, .fiddler\ClientCerts, and others, but none seem to trigger the handshake correctly.

My Questions:

1. What is the exact directory path Fiddler Everywhere uses for client certificates in the latest version?

2. Since I’m using the same cert for multiple domains, do I need to duplicate and rename the file for every single subdomain (e.g., hostname.pfx), or is there a way to map one cert to multiple hosts in the UI/Settings?

3. Does the file extension matter (should I use .pfx, .p12, or rename to .cer)?

   
   

Hi Guys, I have recently downloaded Fiddler. The program itself is great but whenever I close it and I start epic games then there is always a mistake that is not Internet connection. But as soon as I reopen Fiddler, epic games has a connection. Maybe you know what I have to do so that I can start epic games again without fiddler? Thanks in advance

_

Hello,

In my application using FiddlerCore, I see that Windows Search Box on Windows 11 isn't able to make connections to the internet. I would like to be able to get this to work in some way but I'm not sure how.

 

I did some investigation by trying out Fiddler Everywhere and found that the same problems occurs most of the time, except sometimes when the root certificate is installed to machine store. I tried installing the certificate to machine store for my FiddlerCore application but it still didn't remedy the issue. 

 

Please let me know if there's any solution!

Hello

I am currently trying to track any traffic of the game client, but for whatever reason it does not seem to pick up any of it.
All I have found so far was another Thread on this Forum which could not provide the details I need to get the information that I require.

According to the thread the client does not use the windows default proxy.. so what can I do in order to track the traffic?

Any help is appreciated.

~ Dinh

 

 

Hello so as you have seen my subject question is there a way that i could for example in league of legends add myself blue essensce and things like that?

I have a simple problem and hopefully it has a simple solution. I want to limit the speed for an online game, namely Roblox. I edited the line under if (m_SimulateModem), which works great for webpages, but it didn't slow down the game. Is it possible to limit the speed for online games using Fiddler? I believe Roblox uses UDP for communication, so can I edit something to slow UDP communications?

I am trying v5.0.20253.3311 for .NET 4.6.2.

When [File]-[Save]-[All Sessions] and input filename of Session Archive(*.saz) and [Save], 

I see the following dialog: 

Failed to save Session Archive. Could not load file or assembly 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' or one of its dependencies. The system cannot find the file specified.

Please let me know how to solve this problem.

I have a user that reported issues trying to use "Fiddler Everywhere" after upgrading their OS:

"I updated from windows 10 to windows 11...Fiddler Everywhere was working last week when I was using on Windows 10. After upgrading, I tried to use it again today and cannot establish a remote connection to monitor traffic from a mobile device. I noticed when I first opened Fiddler I received a windows firewall notification. The option to "allow" was greyed out and I could only close the prompt. I am assuming the problem with connecting is related to the firewall but these seem to be managed by the organization. Please help allow traffic through Fiddler to assist in my debugging workflows."

I don't use Fiddler, and my team doesn't have internal documentation on troubleshooting Fiddler.  I enclosed some screen captures of what the user has sent us.  He is an Administrator on his Windows laptop, but I noticed some duplicate entries in his Windows Firewall that are grayed out, likely to Group Policy.

Any assistance would be greatly appreciated.

When I attempt to browse to one of my company's websites with Fiddler running, I get the following error on the CONNECT:

fiddler.network.https> HTTPS handshake to site.mycompany.com failed. System.IO.IOException Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. < An existing connection was forcibly closed by the remote host

Fiddler is running under the administrator account and can access most other HTTPS sites (ie, Outlook, Facebook, other company sites).  Things I've tried:

• Installing the Fiddler certificate under Local Machine (that compounded the problem, couldn't access the Telerik site then)
• Tried running IE as administrator
• Added CONFIG.oAcceptedServerHTTPSProtocols = System.Security.Authentication.SslProtocols.Ssl3; in the Main function in Fiddler script.

Any ideas?