Anyone ever see this:  Windows cannot verify username unique because following error occurred while contacting the global catalog

Posted on 2005-05-02
Last Modified: 2009-04-18
I am trying to add a user to AD and I get the following error message:  Windows cannot verify that the user name is unique because the following error occurred while contacting the global catalog:  The server is not operational.  Windows will create this user account, but the user can log on only after the user name is verified to be unique.  Make sure the global catalog is available.  For more information about troubleshooting this issue, see Windows Help.

I just recently demoted a dc and promoted another server to dc.  I am getting this error on my recently promoted dc.  Any suggestions would help.

Question by:stini12
    LVL 95

    Expert Comment

    by:Lee W, MVP
    Do you have a Global Catalog (GC) server?  By default it's the first server.  I'm not sure it's forceably created on another server when you demote it; I don't think so.

    Author Comment

    I have a forest domain blah.lcl and a child domain blah.blah.lcl.  
    How do I check if this dc is the global catalog server?  its part of the blah.blah.lcl domain.

    Author Comment

    I have a forest root domain of datamail.lcl and a child domain of winnt.datamail.lcl.  The global catalog server is within the datamail.lcl forest root domain.  I do not see any dc set as the global catalog server within the winnt.datamail.lcl child domain.  Should there be a global catalog server in both domains?
    LVL 95

    Accepted Solution

    Read more about the GC - if you understand it, you should be able to find which servers are the GC's and how important they are:

    Featured Post

    Why You Should Analyze Threat Actor TTPs

    After years of analyzing threat actor behavior, it’s become clear that at any given time there are specific tactics, techniques, and procedures (TTPs) that are particularly prevalent. By analyzing and understanding these TTPs, you can dramatically enhance your security program.

    Join & Write a Comment

    Preface Having the need * to contact many different companies with different infrastructures * do remote maintenance in their network required us to implement a more flexible routing solution. As RAS, PPTP, L2TP and VPN Client connections are no…
    I guess it is not common knowledge to most Wintel engineers/administrators: If you have an SNMP-based monitoring system in your environment (and it's common to have SNMP or Syslog) it's reasonably easy to enable monitoring of the Windows Event logs,…
    In this sixth video of the Xpdf series, we discuss and demonstrate the PDFtoPNG utility, which converts a multi-page PDF file to separate color, grayscale, or monochrome PNG files, creating one PNG file for each page in the PDF. It does this via a c…
    Here's a very brief overview of the methods PRTG Network Monitor ( offers for monitoring bandwidth, to help you decide which methods you´d like to investigate in more detail.  The methods are covered in more detail in o…

    745 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    13 Experts available now in Live!

    Get 1:1 Help Now