I have a standard website (one Web Application and one Site Collection) with some custom pages and webparts.

The issue I'm having is that when I try to switch users, using the "Sign In As a Different User" and entering new credentials (even for another Site Collection admin account), IE tries the account three times, and then it presents a 401 Access Denied screen.

After that, if I erase all the stuff of access denied page from the browser's url, I'm logged as the new account I just had entered and was not accepted.

After researching for a while on google, I found a KB ( http://support.microsoft.com/kb/970814 ) that might relate, but just tested here and it didn't work at all.

The modified method suggested by the KB is the following:

function LoginAsAnother(url, bUseSource) 

    if (bUseSource=="1")
         //var ch=url.indexOf("?") >=0 ? "&" : "?";

But after making this change, it no longer asks for new credentials.

Any ideas?


1 Answer 1


One of the first things I would do to troubleshoot is to use Fiddler (or other http traffic analyzer) to have a look at the http requests and responses before using the 'Sign in as.." and those after.

It may not give you a direct answer, but by inspecting the headers for each successful request, and comparing with those that are failing with 401 responses, it may give a few clues as to what's going on.

  • tks for the info. I had tried that already, but nothing useful came up - or maybe I couldn't see it :) Apparently the browser (IE) caches the credentials, only fixing Sharepoint's js (init.js) to execute the ClearAuthenticationCache fixes it, but I'm not fond of fixing Sharepoint internal files, as I might have troubles deploying it on my customer's servers. I think it's really weird that only IE's (6, 7 and 8) have this issue, after all it's all MS. I was expecting some KB or SP to fix it, but couldn't find any.
    – Tzn
    Apr 16, 2010 at 13:26

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