Fiddler not capturing traffic from browsers

Question

I ve been using Fiddler for quite a while  but all of a sudden it no longer captures internet traffic   I m on Chrome 29 and Fiddler v4 4 5 1   I ve checked all filters and rules and nothing is on   I ve deleted my rules file  turned on and off capture traffic  and a few other things with no luck   I even uninstalled and re-installed Fiddler to see if that would help but to no avail   What am I missing    Follow Up     Troubleshoot Filters has no effect  I see no activity in the log tab beyond  Fiddler Running     I ve tried multiple browsers and none show internet traffic in fiddler http   localhost fiddler 8888  does not work http   127 0 0 1 8888 works and shows the fiddler echo service

User · Answer

I had the same issue and resolved it by running Fiddler with elevated privileges  aka  Run As Administrator

User · Answer

What worked for me is to reset the fiddler https certificate and recreate it   Fiddler version V4 6XXX   Fiddler menu- gt  Tools- gt  Telerick Fiddler Options     Second tab- HTTPS- gt  Action - gt  Reset All Certificate     Once you do that  again check the check box Decrypt HTTPS certificate

User · Answer

I had the same issue with Firefox  The solution was to set the proxy settings to  system proxy settings   Fiddler can only capture traffic that goes through its proxy server  Capturing was stopped because a few days ago I was tinkering with the Firefox proxy settings for another project   It follows that using Chrome you should also check the browser proxy settings in case of problems with capturing traffic with Fiddler   Read more about this on the Fiddler site

User · Answer

Same problem here  in all browsers  IE  Chrome  FF    Upon startup the Fiddler Log tab showed the following     WARNING Fiddler has detected that system or domain Group Policy has set ProxySettingsPerUser to 0  Unless Fiddler is run Elevated  e g  Run As Administrator   it may not capture traffic from Internet Explorer and other programs  Current process IS running Elevated    I m in a huge corporate environment  with no connection to or info about group policy changes  it apparently just got applied one day   Thanks  bureaucracy     Anyway  that led me to messing around with IE proxy settings   Changing it from Automatic to 127 0 0 1 on port 8888  the default configured port in Fiddler  worked   Kind of a pain  though  because I have to set it each time to override the group policy setting   And then I get cert errors  which is a known thing because Fiddler uses it s own   untrusted cert       and the beat goes on

User · Answer

Make sure you have Capture Traffic enabled by making sure it s checked under File   It s sadly too easy to press F12 by mistake with Fiddler focused and disable the whole thing

User · Answer

As Thomas Glick said  the latests versions of Fiddler2 works ok with all major browsers  But beware  there s a  Show only Internet Explorer traffic filter  in the filters sections  just disable that one and everything should work as expected  including other filters

User · Answer

For it was betternet extension was causing issue  I think any kind of proxy extension installed on Chrome causing issue

User · Answer

Not sure if this is relevant but I had the same problem with Fiddler after the last update  v2 4 5 0    I turned all filters off but still wasn t picking up any traffic   When I unchecked Use Filters on the filters tab  however  all traffic was picked up as normal   I m still trying to figure out how I can use filters when just checking Use Filters box causes all traffic to be blocked

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After hours of googling  reading  uninstalling  facepalming   It turned out that a chrome extension for VPN was handling the proxy settings for Chrome   Betternet to be more specific   Disabling it  solved my problem   To make sure it is not the problem  check the proxy settings for Chrome itself  For me it showed me a message  says   Betternet is handling the proxy settings

User · Answer

I had the same problem  but it turned out to be a chrome extension called hola  or Proxy SwitchySharp   that messed with the proxy settings  Removing Hola fixed the problem

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For me i tried everything on here and eventually it boiled down to a corporate proxy that kept on resetting the INET Settings    I worked my way down the list of suggestions but in the end turned out to be the proxy settings  I had hunch about it but i wanted to be thorogh about it before going to  IT  and saying can i have local bindows proxy settings override please   I asked for the proxy management software to be removed and then within a second fiddler started working  If you cannot override the proxy settings in Internet Properties then fiddler will never work

User · Answer

I encountered the same issue with https and solved it by checking the HTTPS Decryption   Goto Fiddler Options -  HTTPS Check  Decrypt HTTPS traffic

User · Answer

Russian  this info for you  Fiddler didn t capture Chrome traffic because I had installed Antizapret Chrome addon for access blocked by Russian government sites  I removed it and now all works

User · Answer

EDIT  I thought my issue was solved through the WinINET Options  Below are the steps that fixed my Chrome traffic finally being picked up in Fiddler   From Fiddler -  Tools -  WinINET Options -  LAN settings -  Make sure Automatically detect settings is checked    However  what I just found out later was that the PAC script was resetting these options everytime I fired up Fiddler  The real solution was goto Fiddler -  Tools -  Options -  Connections -  Uncheck Use PAC Script  This solved it for good  Below is a screenshot for reference

User · Answer

I too faces similar problem  but once I did the below settings  everything was working fine While working on other application  I selected  No Proxy  setting in browser which I forgot to revert Hence  got this problem    In Fiddler  Goto Teleric Fiddler Options- Gateway   then select  Use System Proxy  recommended   radio button and click on  OK  button and restart Fiddler In your Browser for ex  firefox   Goto Options- Advanced- Network- Settings then select  Use system proxy settings  radio button and click on OK Now try accessing any URL from that browser  and observe they are being recorded in Fiddler If you have applied filters  even they will start working    Hope this helps    Get back to me with any other problems

User · Answer

I ve had the same problem  The solution was to remove proxy from Chrome settings  Also you could have an extension that use proxy  Try to disable it

User · Answer

I had the same problem  when i disabled chrome extension called ZenMate Proxy extension that fixed the problem

User · Answer

I had exactly the same problem  I finally gave up  Reset Chrome s browser settings to default  Uninstalled then reinstalled Fiddler  After that  everything worked

User · Answer

Use Help   Troubleshoot Filters to make sure the traffic isn t getting hidden unexpectedly  Look in the Log tab to see if there s a note about Chrome Group Policy hardcoding the proxy  Update your question to mention whether other browsers  traffic is captured  Visit http   localhost fiddler 8888  in Chrome  What if anything do you see  Visit http   127 0 0 1 8888  in Chrome  What if anything do you see    If you find that steps  1 -  4 don t show anything  this means that Fiddler is unable to set your system proxy information  this might be caused by security or VPN software   Group Policy can also prevent setting  but Fiddler will usually warn you if this is the case    When Fiddler is capturing  click Tools   WinINET Options   LAN Settings and see whether the proxy is set properly  should point at 127 0 0 1 8888   If not  you might try running Fiddler elevated  as Administrator  to see if it makes a difference  It may be helpful to collect a trace using SysInternals  Process Monitor tool  filtered to Registry operations on the ProxyServer registry key   If step  5 doesn t show anything  this means that you have a firewall or some other software interfering with connections to Fiddler

User · Answer

I had the same problem with a Chrome extension called GeoProxy - even though proxy was disabled  it still took the traffic away and stopped fiddler from seeing it  Disabling the extension resolved the issue  I m guessing this will be an issue with any proxy extension    This was meant just as a comment for Claus  response above  which set me on the right path - but apparently I have enough reputation to answer  but not to comment

User · Answer

Might be you have selected non browsers as an option Select Web browsers instead of non browsers

User · Answer

I know this answer is really late  and probably not relevant to what the submitter had 3 years ago  but I found another possible reason why people may not get Fiddler to work  specifically in an Enterprise environment   We are in the middle of releasing Fiddler   For my company  we are not allowed to download apps and install ourselves  We have to request IT to approve it and install it via ordering it from a software  Store  here at the company   To get Fiddler to be available to  order  from that  store   we have to test on test machines   During testing  we could not get Fiddler to update the IE11 proxy settings   When I installed Fiddler myself  it would work  but when I had IT install it using the authorized install channels  what we were testing for   it would not work   Even when we try with users with Local Admin rights  and Run As Administrator  no luck   At first we thought it was a Group Policy thing  but looking into it  it wasn t the case   It turns out the IT people wrapped Fiddler in a VMWare ThinApp wrapper  an invisible VM sandbox to wrap the app inside of   I don t know what the benefits are of ThinApp  but it prevented Fiddler from being able to update the Proxy settings if IE11   When you enable capturing  and open WinINET options in Fiddler  it would show the Proxy settings updated   But when you opened IE11 Connection Settings  the proxy was not updated   Makes sense   So the IT folks decided to release it as a  fat app   that s what they called it  and now it works like a charm   Just wanted to get this on the internet so that people are aware of it

User · Answer

Another possible issue is related to WCF client  this may also include other clients but i m not sure    The client can be configured not to use the machine default proxy  which makes the client application bypass Fiddler capture    For further reading  What is the purpose of usedefaultwebproxy in WCF

[fiddler] Fiddler not capturing traffic from browsers

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