Graeme Bray

Real World Automation and Deployment

Unable to Boot to WinPE (0xc0000001 – a required device isn’t connected)

with 7 comments

When performing builds of servers, you tend to run into some strange errors that cannot always be explained.  Other team members see the problem but you can rarely encounter it.  When you see it, it’s easier to troubleshoot.  We have a VMWare environment running pure VMXNET3 for performance concerns.  We image our systems using MDT and have recently run into the error message shown below:


Status: 0xc0000001

Info: A required device isn’t connected or can’t be accessed.

After much research and some quick testing in our development environment, I was able to find a solution that has, so far, worked fine for our environments.

Run all of the below commands from an elevated command prompt.  I have only tested this on Windows Server 2008 R2 (we are not at 2012 R2 yet and are skipping 2012 Non-R2)

I had to edit the BCD Store to set the maximum TFTP block size to 4096.

To get the block size type: (where d: is your path to RemoteInstall)

bcdedit /enum all /store d:\RemoteInstall\Boot\x64\default.bcd


You must run the above command to get the GUID listed.  This is required to run the TFTP block size command.  To set the TFTP block size to 4096 (or any multiple of 4096), type the following:

bcdedit /store d:\RemoteInstall\Boot\x64\default.bcd /set {GUID} ramdisktftpblocksize 4096



After this command, you must run

sc control wdsserver 129


Trackback to this forum posting that pointed in the proper direction. – Technet Forum Thread


Written by Graeme

January 16, 2014 at 3:58 AM

Posted in WDS

7 Responses

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  1. […] My company has recently started to deploy Server 2012 R2.  Before we could do this, the security team had to develop the policies to apply to the systems before we were allowed to do so.  Naturally, this leads to some times where we have to troubleshoot issues due to restrictive policies.  I started the process to deploy a new MDT server to replace one of my 2008 MDT systems that hosts WDS to attempt to get past the issue documented here. […]

  2. I tried many times to create the ISO file,burn it to DVD successfully in win 7. I get the exact same error message. So the solution posted here also pertains to windows 7?


    March 31, 2014 at 2:37 AM

    • Pedro,
      My solution was strictly based on WDS running on Server 2008 R2. I’ve seen where my solution isn’t always working correctly on my own builds. At this point I’ve started to migrate my builds to Server 2012 R2 to see if that resolves my issues.


      March 31, 2014 at 3:49 AM

  3. Thank you so much!
    This solved an issue i’ve been struggling with for days.


    May 22, 2014 at 4:30 PM

    • Glad that I could help. Beware that I have had issues in my environment that moving to Server 2012 R2 has fixed.


      May 22, 2014 at 9:57 PM

      • i have this error :/
        The set command specified is not valid.
        Run “bcdedit /?” for command line assistance.
        The parameter is incorrect.


        February 3, 2016 at 11:15 AM

      • Are you running your command from an elevated command prompt?


        February 3, 2016 at 6:16 PM

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