Error Message: The User or Group Administrators Is Unknown (256915)

SYMPTOMS

When you attempt to install the Server Extensions, you receive the following error message:

The user or group administrators is unknown.

When you click OK, the installation fails.

CAUSE

This error message occurs when you set the value of the following registry key to 1:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\All Ports\RestrictIISUsersAndGroups

Setting this registry key restricts the user list for the extensions to members of a specific local group. The group names all begin with FP_/LM/W3SVC/# (where # is the virtual server instance to which you are installing). One of the defaults in the installation is the Administrator for the user account or group, who is the Web Administrator for the Web server. The local Administrators group cannot be a member of another local group (FP_/LM/W3SVC/#).

WORKAROUND

To work around this issue, do one of the following:

When you are presented with the dialog box that reads, "Which Windows Group or user account should be the Web Administrator for this Web Server?" replace Administrators with a member of the FP_/LM/W3SVC/# group. If the Administrator account is a member of the FP_/LM/W3SVC/# group, you can use that account. The installation then continues and completes.-or-
Do not set the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\All Ports\RestrictIISUsersAndGroups registry key at the global level. Instead, set it in the following location after you install the Server Extensions:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\Ports\Port /LM/W3SVC/#:
Note that this registry key is not created until you install the Server Extensions.

MORE INFORMATION

For additional information, click the article numbers below to view the articles in the Microsoft Knowledge Base:

214515 How to Determine which Virtual Server References

236464 Restrict Users and Groups in FrontPage 2000 on IIS