Q. I'm trying to install the Microsoft Exchange Server Clustered Mailbox Role, but I get a Microsoft IIS error related to a dependency not being available. What's wrong?

A. First, make sure you've installed the required prerequisites:

  • ISAPI Extensions
  • Basic Authentication
  • Windows Authentication
  • IIS 6 Management Compatibility

The common cause for this error if you meet the prerequisites is that your .NET installation is incomplete or corrupt. When you attempt to install the Clustered Mailbox Role, you'll get the following error.

An error occurred while creating the IIS virtual directory
'IIS://savdalex01.savilltech.net/W3SVC/1/ROOT/Exchange' on
'savdalex01'. Could not load file or assembly
'Microsoft.Web.Administration, Version=,
Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of
its dependencies. The system cannot find the file specified.

The solution is to reinstall .NET 3.0, even though it may show as installed. This should resolve the problem.

Related Reading:



Check out hundreds more useful Q&As like this in John Savill's FAQ for Windows. Also, watch instructional videos made by John at ITTV.net.
Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.