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Greetings,

I am trying to figure out an issue that I was given. There are two apps A and B. 

A is used to authenticate users and passes a token to B and B adds a cookie. Something strange happens when the cookie expires or after a hard browser reset. 

 

WITHOUT FIDDLER: 

User hits app A enters credentials and gets forwarded to app B. However, for about 5 seconds the browsers black "xxx took too long to respond" error screen shows but then magically the default page is rendered soon afterward. This only seems to occur when the cookie has expired or after an extended amount of time.

 

WITH FIDDLER: (SEE SESSIONS 61, 71 and 83)

When I perform the same scenario in fiddler, where I would expect the black "xxx took too long to respond" screen, I get the certificate error screen attached with the open lock icon. I have to dismiss that three time. While I am dismissing the ssl tunnel errors the default user page is rendering.

The correlation is about the same time I get the lock dialog(s) in fiddle is the same place I get the black browser error screen and the app seems to be loading in the background and the refreshes once fully loaded.

My thought is there is a https-->http request being "partially" blocked from A-->B as B is http only with no certs. The devs tell me they can't find a request being made that is https. So, I can't figure out where the ssl tunnel is coming from (see screen capture). My thoughts are.

1. The devs missed something and one of the calls is http.

2. Some network appliance is attempting to convert the call to https, though there are no url rewrites on the IIS server. 

 

Any input would be helpful. Can anyone see what would cause a black "xxx took too long to respond"  to render while the default page is loading. It feels like one of those weird scenarios where the request was changed before it was fully read or something else arcane like that.

 

Nick Iliev
Telerik team
 answered on 27 Mar 2024
0 answers
3 views

1) Fiddler didn't hint for most top-level user class name anymore. For example, the following code:

  • If I type code at **, it'll hint all system class without Xyz1 but it shows Xyz2.
  • If I type "Xyz1." then it hint "Xyz3" so it seems to see fields/methods inside properly.

I use Fiddler in another PC (PC2) which report the exact same version (and editor's version), it hints my class properly.
*PC2 that works well has a bit lower WinNT part "WinNT 10.0.18363.0"

class Xyz1 { //Try both public, class
public static class Xyz3 {

}
}
class Handlers
{
static class Xyz2 {

}
public static function xx2(){
**
}
}

The scenario:

"Before this", I think Fiddler hint it in current PC (PC1) too. But it's abruptly missing so I try typing the new class. It hints the new class but not for the class I'll use. So I was dumbfounded and reset the script (delete the file) and retest. Because I know some pattern of code may break Fiddler format. Then "Handlers" is not in the list so I'm sure it's not about the format. I want to confirm that it normally hint top-level class name so I check it in my PC2, and it did. Then I completely uninstall-reinstall Fiddler in PC1. It fails it list any user class. I also try to swap the script to test between PC1 and PC2. PC1 always not work and PC2 always work. *I did not try to reinstall on PC2 though because it's heavily used. But it has the exact same version.

2) Script editor from "Customize Rules..." menu change after close and open it for the 2nd time - even without restart Fiddler Classic. Folding feature is missing and comment will be green instead of gray as after fresh install Fiddler Classic. I usually use this variant though, maybe because the gray comment version is found only once after fresh install. Embedded editor in tab is green with folding though. But problem 1) hint never work anywhere.

Ryuu
Top achievements
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Iron
 asked on 25 Mar 2024
1 answer
3 views
Trying to debug a chunked encoding response that looks correct to me. But when clicking on decode in response inspector I get the error "HTTP Error.. The chunked content is corrupt. Chunk Length was malformed. Offset 19". 
My question is, why does Fiddler think this is corrupt as the chunk lengths and encoding seems correct. And more specifically, how do I know what position "offset 19" is referring to so I can investigate further?
Nick Iliev
Telerik team
 answered on 25 Mar 2024
1 answer
22 views

Good afternoon,

We have installed Fiddler Classic on a Windows 11 laptop specifying install directory within Program Files, as per https://feedback.telerik.com/fiddler/1441442-default-install-fiddler-for-all-users, and it is not installing correctly. It just dumps the files in the folder. No Start Menu entry anywhere, no entry in the machine Uninstall registry. Key is however created within the installing users Uninstall key. Same issues if the installer is sent via management software, e.g. SCCM. Only here there is no registry entry created at all. This does not follow basic principles for software for management in a corporate environment, or frankly any other environment than that of a skilled personal user.

I have searched your forum and there is nothing recent to this post for machine-wide / corporate installs. As this "solution" was from 2019 and advises that it may cause issues with extensions, I expect that now, 4-5 years later, you have since sorted your installer out?

Tried to uninstall manually from the install directory using your uninst file located there and this fails stating: "A Progress Telerik Fiddler Classic component appears to be running. Please close all Progress Telerik Classic-related applications and try again." There is no process running called Fiddler, and looking through the list there is nothing obviously linked to your software. System has been restarted and same issue. Had to login with another user to uninstall. This is not appropriate. Please provide a full listing of your processes. Quite frankly, your software is acting more like malware.

Do you have a machine-wide installer please? A working one. The current state for deployment of your software is appalling.

Regards,

Craig.

Nick Iliev
Telerik team
 answered on 21 Feb 2024
1 answer
15 views
How can I exempt all in FiddlerCore as if I was using the Win Config option in Fiddler Classic? Thank you in Advance!
Nick Iliev
Telerik team
 answered on 21 Feb 2024
1 answer
19 views

Hi, i have lots of error sessions with responseCode 504 which boring,and i try:

 

if(oSession.responseCode == 504){

    oSession["ui-hide"]="true";

}

it doesn't work any all.

Can someone help me,please

ps:

the fiddler log shows some thing special:

Fiddler.Network.ProtocolViolation - [#6691] The Request's Host header did not match the URL's host 

URL Host: connpm.gj.qq.com:47873
Header Host: connpm.gj.qq.com

and the req headers are:

POST http://connpm.gj.qq.com:47873/q.cgi HTTP/1.1
Host: connpm.gj.qq.com:47873
Connection: Keep-Alive
User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0)
Accept: */*
Content-Type: application/octet-stream
Content-Length: 430
ProxyConnection: Keep-Alive
Pragma: no-cache

......

Nick Iliev
Telerik team
 answered on 12 Feb 2024
1 answer
18 views

Hello,

We have an Exchange Server behind e FortiWeb in a reverse proxy mode.

is it possible to test if a reverse proxy config really works? 

 

thanks

Nick Iliev
Telerik team
 answered on 12 Feb 2024
1 answer
14 views
When i capture traffic and try to load something on the page i get logged out...... when i turn capturing off and reload the page everything is fine all pages load fine .... is this a Security issue like a WAF?? a Captcha issue ? or a Cloudflare Issue?  I have tls1.0, 1.1 and 1.2 enabled
Nick Iliev
Telerik team
 answered on 05 Feb 2024
1 answer
24 views

Hi,

 

There is an issue with the Progress Telerik Fiddler Web Debugger.

When the system is trying to connect with a websocket endpoint which can't be reached it won't show up in the stream.

It's just completely missing. I would expect that the the websocket should show up in red with a 404 result.

Nick Iliev
Telerik team
 answered on 30 Jan 2024
1 answer
18 views

I am developing a Chrome extension that activates a proxy. When I enable the VPN and reload the page, the following steps should occur:

1. The Chrome browser makes a request to the proxy.
2. The proxy sends a response with a 407 code.
3. Chrome should call chrome.webRequest.onAuthRequired and provide credentials to the proxy.

However, I don't see any browser interactions with the proxy server.

Is it possible to observe the interaction between Chrome and the proxy using Fiddler?

Nick Iliev
Telerik team
 answered on 25 Jan 2024
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