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Fiddler messing with my pc internet Help I'm completely lost. (NOOB)

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Kyle
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Kyle asked on 10 Jan 2021, 07:29 AM
I am completely new at this fiddler thing and I have no idea what it does. I just know that I can't connect to anything without having fiddler on otherwise it just keeps loading and says I cannot connect to the internet. I used it to find a value in a game and I am stuck using fiddler to just gain access to the internet. I uninstalled it and everything and it will not go back to the way it was. I want nothing to do with this program anymore I just want my pc back for everyday use without having to launch fiddler every time to connect to discord or steam or the internet etc. I have tried checking and unchecking "capture https CONNECTs" many times. I have reset all certification multiple times. I have also went in a deleted all the ones from fiddler and nothing changed. I also know if I don't use "act as system proxy on startup" I cannot access the internet. Thanks.
liu
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commented on 28 Nov 2022, 06:12 AM

I met the same problem in the morning, and I assumed that the fiddler must be accountable because I just installed it and absolutely ignorant of this application. So, I searched with a keyword 'fiddler caused connection failed' in many searching engines and got no answer. Eventually, I seek help from my laptop's official supporters. They instructed me to restart my VPN then the connection is restored just like a miracle. It seemed that my problem was caused by my carelessly shutdown the laptop without normally disconnecting VPN. If only the experience can enlighten you or other people who meet the same problem.

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Rosen Vladimirov
Telerik team
answered on 11 Jan 2021, 03:24 PM

Hi Kyle,

I'm sorry to hear about your issue using Fiddler Classic. By default, when Fiddler captures traffic, it sets itself as system proxy on your machine. When you close Fiddler, the system proxy settings should be updated and should not point to Fiddler anymore. However, it seems the last part does not happen on your machine, which is why you do not have internet access when Fiddler is not working - the proxy setting point to Fiddler, but it is not running. 

In order to resolve this, you can close Fiddler and open your proxy operating system settings (just write down Proxy in your Start menu). At the bottom of the page find the switch for proxy configuration and turn it off. Now you should have internet access even when Fiddler is not working.

Hope this helps.

Regards,
Rosen Vladimirov
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Jackson
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commented on 06 Nov 2023, 01:06 AM

Hello, Im having the same problem as OP, I followed you're instructions, and nothing changed, I did uninstall and reinstall fiddler if that might have an effect, any ideas?
Nick Iliev
Telerik team
commented on 06 Nov 2023, 08:04 AM

Hello Jackson,

Based on my colleague's explanation, the system proxy settings should be reverted if the system settings are reverted to their original state (with Fiddler turned off). Uninstalling and reinstalling Fiddler will not affect the pre-set system proxy. However, if you are using a VPN then you might need to disconnect the VPN and then ensure that your system proxy settings are reverted to their original state - then restart the VPN and retry the internet connection.

Jackson
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commented on 13 Nov 2023, 01:56 AM

Im not using a VPN
Nick Iliev
Telerik team
commented on 13 Nov 2023, 06:31 AM

Hey Jackson,

 

If you are using Fiddler Everywhere, you can investigate possible issues by checking the application log files.

Regardless of whether you are using Fiddler Classic or Fiddler Everywhere, it is essential to ensure that your active network connection's proxy settings are reverted to their original settings after closing the proxy application. To verify this, close Fiddler and check the OS proxy settings. If the issue persists, please contact your network administrator.

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brent
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Iron
answered on 14 Jun 2022, 10:06 PM

I have had a similar, but slightly different experience myself.

After installing this and using it to capture some traffic I then uninstalled it and now the entries in my host file no longer work. They were working perfectly before this.

I have looked through every config file on my PC to look for changes to default Proxy, I have ensured that there are no proxy settings enabled in the internet options and the system proxy settings and nothing.

Based on some research it really appears like the uninstall process has some issues.

Rosen Vladimirov
Telerik team
commented on 16 Jun 2022, 05:38 PM

I've tried to reproduce this behavior, but without success. Did you edit the hosts file through Fiddler Classic or you did it manually?
How did you uninstall the application?
If you can provide steps to reproduce the problem, we'll be able to dig into the issue and see what's going wrong.
brent
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commented on 16 Jun 2022, 06:10 PM

My hosts file already pre-existed prior to installing fiddler with custom entry inside it.

After installation, they all stopped working.

I uninstalled the application using add/remove programs, and it still wasn't working.

After some digging, it appears as though the install process, or something within fiddler itself may have adjusted the http listeners on my machine, which was not obvious. After fixing that, they are now working again.

Rosen Vladimirov
Telerik team
commented on 21 Jun 2022, 01:12 PM

Thanks for the provided steps. I've tried them, but I'm still not able to reproduce the issue. We'll continue trying and hopefully find a way to reproduce it and fix this undesired behavior on our side.

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Kyle
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Rosen Vladimirov
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brent
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Iron
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