"Adprep was unable to update" or "Windows cannot determine the local sysvol location" error message when you run Adprep.exe in Windows 2000 Server or in Windows Server 2003

When you run the Adprep.exe /domainprep utility on a computer that is running Microsoft Windows 2000 Server or Microsoft Windows Server 2003, you may experience the following issues:

• You receive the following error message:
  Adprep was unable to update domain-wide information. Adprep requires access to existing domain-wide information from the infrastructure master in order to complete this operation.
• The following error is logged in the Gpupgrad.log and Adprep.log files:
  Windows cannot determine the local sysvol location. Upgrade of Domain Group Policy Objects failed. (The system cannot find the file specified.)
  Note The Gpupgrad.log and Adprep.log files are stored in the following folder:
  C:\Winnt\System32\Debug\Adprep\Logs

This issue may occur on a computer that has a missing or incorrect registry entry.

Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To resolve this issue, you must create the missing registry entry, or you must correct the incorrect registry entry. To do this, follow these steps:

1. Click Start, click Run, type regedit in the Open box, and then click OK.
2. In Registry Editor, locate and then right-click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters
3. If the SysVol registry entry is not present in the right pane, create it. To do this, follow these steps:
   1. In the left pane, right-click Parameters, point to New, and then click String Value.
   2. Name the new entry SysVol, and then press ENTER.
4. In the right pane, right-click SysVol, and then click Modify.
5. In the Value data box, type the path of the Sysvol folder. By default, this path is C:\Winnt\Sysvol\Sysvol.
6. Quit Registry Editor.