SCCM OSD – “A required device isn’t connected or cannot be accessed”

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We today ran into an issue where our SCCM OSD PXE boot was not working. It was coming up with a very confusing message stating:

“A required device isn’t connected or cannot be accessed”




This led us to start looking at the hard drive and the drivers, however, the solution was completely different.

The problem was that the RamDiskTFTPBlockSize we were using on our distribution point was too high, so we had to lower it to the Microsoft default.

To do this, you should follow these steps:

  • Go into regedit on your distribution point server
  • Browse to HLMSOFTWAREMicrosoftSMSDP
  • Find the RamDiskTFTPBlockSize key
  • Edit the decimal to “1456”
  • Close regedit
You should then retry your PXE boot sequence and you should find that it now works.
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1 Response

  1. Andreas says:

    Very nice article! This was the solution for us having problems with pxe boot on citrix virtual desktops.
    Thnak you!

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