WDS: Required Device isn’t connected or can’t be accessed

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Learn how to solve a recent issue with your Windows Deployment Services causing the error message “A required device isn’t connected or can’t be accessed. Error code: 0xc000000f”

If you are using the Windows Deployment Service and/or Microsoft Deployment Toolkit, you might recently get an error message while your client downloads the deployment image:

Error A required device isn't connected or can't be accessed. Error code: 0xc000000f

Error message: A required device isn’t connected or can’t be accessed


The error message says: A required device isn’t connected or can’t be accessed. Error code: 0xc000000f.

That error message is caused by the March 2019 cumulative update for Windows Server.

Currently there is no solution provided by Microsoft, but you can mitigate the issue by changing some settings in your WDS.

Open your Windows Deployment Service console and right-click on the server. Then select “Properties”:

In the new window, select the TFTP tab.
Here deselect the “Enable Variable Window Extension”.

Now restart the Windows Deployment Services Server service (WDSServer) and retry deploying an image.

If you still getting an error, go back to the TFTP settings and change the “Maximum Block Size” to 1456 or (if the problem still persists) to 16384 and restart your service plus run it again.

I hope this solves your issues. Let me know in the comments.

12 thoughts on “WDS: Required Device isn’t connected or can’t be accessed”

  1. Thank you, I have been having this issue since mid March. I have been doing installs from USB (which does not have my images set up with programs and settings) and having to do it all manual. Clearing the checkbox fixed it.

  2. Dude, you saved my bacon with this. I reconfigured my WDS and MDT server for the Windows 10 1903 update, and everything stopped working, with exactly this error. Your fix worked when nothing else would. Thanks again.

  3. Deselecting the option and configure on 1456 + restart de service worked for me. I installing Win server 2019. Many thanks!

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