Hi all i have one issue please help me. I have a subsite page ( https://mymossportal/Test ) where i am logged in with any user on my site say user1. when i click on sign in as a different user and enter credentials for same user i.e user1 again then the site does not accepts the user and it redirects me to page with NOT AUTHORIZED message. but this issue is not with main site collection i.e https://mymossportal/pages/default.aspx it seems like a bug in sharepoint need help from you guys .

Hi I don't think this is a bug. In SharePoint no matter you click sign in as a different user from a root site or a sub site, it will display 401 UNAUT HERIZED when you enter the same credentials in the login prompt. This is a by-design behavior. I suggest you follow the steps below to test if this issue will happen again: 1. Go to Tools of your IE browser and click Internet Options 2. Click Delete under Browsing history and click delete all 3. When the deletion finishes, click OK 4. Open a new IE window and log in the root site twice with the same credentials to see if this time you will got 401 UNAUT HERIZED message. Hope this helps. Lu Zou

Thank you Lu Zou. It is indeed a "By-Design". It also happens on SP2010. But what I don't understand is, why is this such, because if the current user credential is being entered, logically it should be able to authenticate, correct? I wonder if there are any technical reasons for this? Thank you.