SharePoint Keeps Prompting for Credentials

Problem

SharePoint keeps prompting you for credentials in the following scenarios:

1. You get prompted for credentials when you access the site in the browser.
2. You get prompted for credentials when you open a document from SharePoint.
3. You get prompted for credentials after you open a document from SharePoint and try to “Save As”.

Cause

The most likely cause of your problem is that you are using an FQDN for SharePoint (For example, sharepoint.company.com) and your client machine runs Windows 7. By default, Internet Explorer and Webdav assume that this address is on the Internet and as a security measure, does not automatically pass in your credentials.

Solution

If your scenario is the same as above, then you will need to do two things.

1. Add your SharePoint server’s FQDN to your Trusted Sites or Intranet Sites zone.
2. Modify your registry settings for the WebClient service.

Add your SharePoint server’s FQDN to your Trusted Sites or Intranet Sites zone.

If using Trusted sites, ensure that you do not select “Require server verification (https:) for all sites in this zone”.

1. Internet Explorer -> Internet Options -> Security -> Trusted Sites -> Sites
2. Add the URL(s) of your SharePoint server(s).
3. Click OK
4. Click Custom Level -> Scroll to the bottom -> User Authentication
5. Ensure that it is set to Automatic logon with current user name and password

If you are using the Intranet Sites zone, note that you need to manually add the SharePoint server URL under Advanced settings.

1. Internet Explorer -> Internet Options -> Security -> Local Intranet -> Sites -> Advanced
2. Add the URL(s) of your SharePoint server(s).
3. Click OK
4. Click Custom Level -> Scroll to the bottom -> User Authentication
5. Ensure that it is set to Automatic logon with current user name and password

Modify your registry settings for the WebClient service.

1. Open Regedit, Start -> Run -> regedit
2. Browse to the location: Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\WebClient\Parameters
3. Create a new Multi-String Value and call it AuthForwardServerList
4. Under Value data: Type in the URL of the SharePoint sites, one on each line. You may use wildcards.
5. Click OK.
6. Open Services console, Start -> Run -> services.msc
7. Look for the WebClient service, and click on Restart.

 References

http://support.microsoft.com/kb/943280/en-us