Error: AccessDenied (0x271d).

[Rupam Roychoudhury]

I am suddenly getting the following error in al web browsers except Firefox and tor.
The connection to 'www.google.com' failed. A Firewall may be blocking Fiddler's traffic.
Error: AccessDenied (0x271d). 
System.Net.Sockets.SocketException An attempt was made to access a socket in a way forbidden by its access permissions 216.58.199.132:80 (this changes time to time)

Does anyone has a solution for it ? Which is the exact service blocked by firewall that caused this?

I am mostly getting  Host: accounts.google.com:443... and error 502.

[Eric Lawrence]

Typically this means exactly what it says-- you have a firewall on your PC which is blocking outbound network requests from Fiddler.exe. You need to configure your firewall or other security software to permit Fiddler to talk to the network.

What version of Windows are you running, and what security software is installed?

[Rupam Roychoudhury]

The exact message is

The connection to 'www.google.com' failed. A Firewall may be blocking Fiddler's traffic.
Error: AccessDenied (0x271d). 
System.Net.Sockets.SocketException An attempt was made to access a socket in a way forbidden by its access permissions 216.58.199.132:80

This message only appears in chrome,opera,safari,IF 11.....Mozilla firefox and Tor works fine.
I am using AVG internet security in windows 8.1,where if firewall is disabled everything works fine.Maybe there is some specific service that needs to be put in exception in it.

[Eric Lawrence]

You don't need to exempt a service, you need to exempt the browsers.

[Rupam Roychoudhury]

I found out the exact reason behind it after 3 days research,
It is nothing but a virus.Called something like http=127.0.0.1:8080;https=127.0.0.1:8080,which changes the proxy settings from automatic to manual 127.0.0.1:8080 again n again.
I found it with updated version of Malwarebytes Anti-Malware and removed it.
It came with install shield wizard update,while connected to internet connection it gives a notification to update windows to windows 10.
Following registry were effected,
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\NlaSvc\Parameters\Internet\ManualProxies
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NlaSvc\Parameters\Internet\ManualProxies
HKLM\Software\Policies\Microsoft\Internet Explorer\Control Panel  
HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings  
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Internet Settings\Connections   
Manual change in this registry entries wont help unless the virus is removed.And most antivirus (I used AVG IS) and anti-spyware failed to detect it.

this also change LAN settings to "this settings are managed by system admin" Unless you open ID as an admin and go to it.
changing this reg. entry "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Internet Explorer\Control Panel" from 1 to 0 only helps until you restart.

[Davorin Jurišić]

I'm having the same issue. All browsers are blocked from accessing the internet even with adding them in AVG firewall's allowed rules. Also My.Com game center app (for Armored Warfare free to play) is blocked by firewall.

I found another possible solution as it wasn't that proxy.pac virus. completely clean up antivirus (for me i used AVG remover to remove avg internet security). Then I installed it again but without Email scanner - on another google group that was the solution.

IT WORKED!!!!