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1 answer
7 views

Hello,

i try to read a capfile created by zscaler. But Fiddler gives a error. 
Any idea how to solve that?

Regards,

 

René

Nick Iliev
Telerik team
 answered on 22 Jun 2026
1 answer
9 views

Hello,

i have a pcap file exported from zscaler. when reading it into fiddler classic the error attached in the screenshot is displayed.

how can i solve it?

 

regards,

 

René

 

Nick Iliev
Telerik team
 answered on 22 Jun 2026
1 answer
86 views

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)?


Nick Iliev
Telerik team
 answered on 06 Apr 2026
2 answers
2.1K+ views
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
Nick Iliev
Telerik team
 updated answer on 06 Apr 2026
5 answers
2.1K+ views
_
Nick Iliev
Telerik team
 updated answer on 06 Apr 2026
4 answers
1.5K+ views

Hi, i get this error on any site any browser, 

when i looked at the certificate list, i see that the certificate is expired:

 

i just reinstalled the last version, but the problem persists

is there any way to fix that ?

Hardy
Top achievements
Rank 1
Iron
 answered on 11 Feb 2026
1 answer
54 views

I need Fiddler to capture my call from nodejs. 

I call https://domain from nodejs like this

  import { ProxyAgent, fetch } from 'undici';
  const dispatcher = new ProxyAgent('http://127.0.0.1:8888' )
   var r2 = await fetch('https://domain', {
	method: 'POST',
	dispatcher,
	headers: {	
                 ...}
	  },
    body:  ...
  }
  );
  var r2data = await r2.json();

I can do the above call to http://domain, but when I changed to https://domain, I got the below error, any idea how do I handle this? thanks

  [cause]: Error: unable to verify the first certificate
      at TLSSocket.onConnectSecure (node:_tls_wrap:1674:34)
      at TLSSocket.emit (node:events:519:28)
      at TLSSocket._finishInit (node:_tls_wrap:1085:8)
      at ssl.onhandshakedone (node:_tls_wrap:871:12)
      at TLSWrap.callbackTrampoline (node:internal/async_hooks:130:17) {
    code: 'UNABLE_TO_VERIFY_LEAF_SIGNATURE'
Nick Iliev
Telerik team
 answered on 06 Feb 2026
1 answer
48 views

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!

Nick Iliev
Telerik team
 answered on 19 Jan 2026
1 answer
482 views

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

 

 

ivory
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Iron
Iron
 updated answer on 12 Jan 2026
2 answers
1.9K+ views
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?
ivory
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Iron
Iron
 updated answer on 12 Jan 2026
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