Fiddler not working on Windows 2012 R2 - Loopback Exemption failing

[Camillo Anania]

Hi All,

I have searched around extensively and did not found any solution to the following problem. I found different people around asking similar question but it seems no one provided any definitive information to make Fiddler working on Windows 2012 R2 even if I understand the OS is supported.

I am running Fiddler 4.6.2.3 on Win 2012 R2 Amazon VM and it is not capturing any traffic.

When I try to use the bundled 'AppContainer Loopback Exemption Utility' (aka the WinConfig button) I get following error:

>> "Unable  to use NetIsoEnumAppContainers to get AppContainer list. Error code: 0x0"

>> Attempting manual registry crawl; some information will be unavailable.

After clicking ok on first error then getting second error:

>> The utility was unable to collect the list of AppContainers on this system.

>> [NetIso ErrorCode 0x0] - Unable to enumerate AppContainers.

Did anyone was able to run Fiddler on Win 2012 R2? Anyone can provide some guidance how to fix the issue?

Thanks,

Camillo

[Camillo Anania]

No feedback at all?

Thanks,

Camillo

[Michael]

Hi there!

I started a brand new virtual machine on AWS with Windows 2012 R2 and I'm having the same problem you have described, I found some other folks having the same issue here https://mymemorysucks.wordpress.com/2013/11/12/issues-with-fiddler-on-windows-8-1-and-ie-11/.

I didn't go that deeper so I cannot tell if it worked for me.Maybe someone from the community can share their insights?

Thanks.

[Camillo Anania]

Hi Michael,

read that. Unfortunately that article does not help for Windows 2012 R2.

Thanks,

Camillo

[EricLaw]

"any traffic" from which applications? Only Internet Explorer (potentially) uses AppContainers; Chrome and other browsers do not.

Can you follow the steps here: https://groups.google.com/forum/#!topic/httpfiddler/SsZnGxdxklg and post the results?

[Camillo Anania]

Hi Eric,

thanks for the tips, below all requested information:

   0. which application -> I would like to make it working with Chrome, I have tried both IE and Chrome without success

   1. On Fiddler’s Help menu, click Troubleshoot... and navigate your browser somewhere. Does traffic appear in Fiddler? -> Navigating to my target page using Chrome Fiddler is listing only events where the Host = 'Tunnel to', nothing else.

   2. In your browser, visit http://ipv4.fiddler:8888/. Does anything appear in Fiddler or your browser? -> 2 events appearing both for Host = 127.0.0.1:8888, first one with URL = /, second with URL = /favicon.ico

   3. In your browser, visit http://localhost:8888/. Does anything appear in Fiddler or your browser? -> 2 events appearing both for Host = localhost:8888, first one with URL = /, second with URL = /favicon.ico

   4. client used: Chrome both 32 and 64 bit version 51.0.2704.84 m

   5. the URL I am attempting to load is an HTTPS over internet

   6. Fiddler version used: v4.6.2.3

   7. same version of Fiddler + Chrome working fine on Win7 when I am accessing the same URL under test

   8. in log there are only few entries like: "HTTPSLint> Warning: ClientHello record was 508 bytes long. Some servers have problems with ClientHello's greater than 255 bytes. https://github.com/ssllabs/research/wiki/Long-Handshake-Intolerance"

Let me know if any further info is required.

Thanks,

Camillo

[EricLaw]

1. Do the pages load in the browser?

2. Have you enabled HTTPS decryption on that PC?

3. If you examine the "Tunnel to" (Connect tunnels), what do you see in the TextView response inspector?

[Kevin McKinney]

I'm also unable to run the enable appcontainer loopback utility on Windows Server 2012 - I get the same two errors. Tried both within Fiddler and running it as a standalone. Confirmed that Windows firewall is off, and that it works fine on Windows 10.

[EricLaw]

To be clear, if the Windows Firewall service is disabled (the service not just the frontend), then AppContainer traffic restrictions are not applied and you don't need to run the AppContainer Loopback exemption tool at all.