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1 answer
7 views

Fiddler classic doesn't capture anything because there's a security software in my case that always changes the proxy setting if I change it for Fiddler.

Fiddler Anywhere feels like a hack. It's only good for capturing when launching a browser from within it.
There's no functionality to capture http requests that come out from apps running on the machine. No capturing from apps that host browsers like webview.

Please make a tool that can capture requests from any app. See httpdebugger.com as an example. The tool need not depend on a proxy.

Nick Iliev
Telerik team
 answered on 04 Nov 2025
1 answer
19 views

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.

Nick Iliev
Telerik team
 answered on 17 Oct 2025
1 answer
30 views
Receiving this error: 

[2025-09-25 16:50:27:054] [Error] [Fiddler] !SecureClientPipeDirect failed: Org.BouncyCastle.Tls.TlsFatalAlertReceived illegal_parameter(47) for pipe (CN=*.facebook.com, O=Progress Telerik Fiddler, OU=Created by http://www.fiddler2.com)
Nick Iliev
Telerik team
 answered on 26 Sep 2025
2 answers
941 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 ?

Nick Iliev
Telerik team
 updated answer on 15 Sep 2025
1 answer
76 views
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.
Nick Iliev
Telerik team
 answered on 13 Aug 2025
3 answers
11.7K+ views

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?

Elly
Top achievements
Rank 1
Iron
 answered on 04 Aug 2025
1 answer
39 views

Hi

I recently downloaded the fiddler classic and it's crash when opening. And i already tried almost ways to fix it. And the log show that the MSVCR80.dll module error when the fiddler classic started.And  I Already reinstall the Microsoft Visual C++ 2005 Redistributable but it doesn't work. Could you please help to fix the crash?

Nick Iliev
Telerik team
 answered on 21 Jul 2025
1 answer
49 views

Hi,
I'm unable to access DuckDuckGo with Fiddler Everywhere. I can connect to DuckDuckGo without Fiddler. I think it's because DuckDuckGo detects Fiddler. Other possibilities are that the Fiddler certificate also supports unsafe TLS 1.0 and TLS 1.1, and their server ignores the request, but I'm not sure. Can you connect to DuckDuckGo, or is this issue exclusive to me? Thanks

This is what I received in the response. 

Nick Iliev
Telerik team
 answered on 16 Jul 2025
1 answer
45 views
Delete my account
Nick Iliev
Telerik team
 answered on 14 Jul 2025
1 answer
50 views

I need to capture URLs for Oracle SmartView logins. I saw some video for fiddler classic to setup. but can you help me to do the same set up ln enterprise.

https://youtu.be/syUoIw8N2WQ

pls provide the steps for enterprise:

 

Maria
Telerik team
 answered on 23 Jun 2025
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