Fiddler causing 401 error in IE

[Kettch]

I wish I could pinpoint this to whether or not it started with one of the latest updates, but I'm not certain...

What's happening is that with Fiddler capturing, IE 11 (on Windows 7) is getting 401 errors when trying to connect to a service being run as part of a web application. It just started happening in the past few days. If stop capturing, it starts working again.

Please let me know if there is more information that you need.

Thanks

[EricLaw]

It's not entirely clear what you mean here: a HTTP/401 is sent by the server to ask a client for credentials. It is expected that the client will see the 401 and reply with its credentials.

If you're saying: "I used to get 401s but then 200s, but now I only get 401s" the explanation may be that the server enabled "Extended Protection - Channel Binding Tokens".

Does ticking the Rules > Automatically Authenticate menu item fix it?

http://blogs.msdn.com/b/fiddler/archive/2011/09/04/fiddler-http-401-authentication-workaround-to-support-channel-binding-tokens-removing-endless-prompts.aspx