You cannot download shared resources on a Windows Server 2003 domain controller by using BITS 2.0 if the UNC path of the server points to itself

On a domain controller that is running Microsoft Windows Server 2003, a download is unsuccessful when the following conditions are true:

• You use Background Intelligent Transfer Service (BITS) 2.0 to try to download shared resources from the domain controller itself.
• You use the Universal Naming Convention (UNC) path of the domain controller for the download.

You do not experience this problem when you use the UNC path of another server. You also do not experience this problem when you use the UNC path of the domain controller from another computer.

This problem occurs because of a problem in BITS 2.0.

BITS 2.0 uses the Windows Server 2003 redirector. Because of the shadow loopback feature in Windows Server 2003, an operation that uses the UNC path of the local server is typically interpreted by BITS 2.0 as a direct disk I/O operation. Therefore, BITS 2.0 does not use the Windows Server 2003 redirector for the operation.

To work around this problem, use one of the following methods.

Method 1: Map the shared resources to a drive

Map the shared resources to a drive. Then, use that drive to download the shared resources.

Method 2: Disable the shadow loopback feature

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

Add the DisableShadowLoopback registry entry to the Windows registry. Then, enable the entry. To add this registry entry, follow these steps:

1. Click Start, click Run, type regedit in the Open box, and then click OK.
2. In the left pane, locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MRxSmb\Parameters
3. On the Edit menu, point to New, and then click DWORD Value.
4. Type DisableShadowLoopback, and then press ENTER.
5. Double-click DisableShadowLoopback.
6. In the Value data box, type 1, and then click OK.
7. Quit Registry Editor.

Typically, the Windows Server 2003 redirector uses the shadow loopback feature to decide whether the local file system should handle an I/O operation. However, when you use BITS, the redirector handles the I/O operation even if the local file system would otherwise handle the operation.