June Update KB4503276 blocks PXE boot on SCCM DPs

[German]A brief warning for administrators using Windows Server 2012 to deploy via SCCM. The June 2019 update KB4503276 causes trouble because it prevents PXE booting (WDS). Microsoft has now confirmed the problem.


Update KB4503276 for Windows Server 2012 R2

Update KB4503276 is the June 2019 rollup update for Windows 8.1 and Windows Server 2012 R2 that was released on June 11, 2019. Microsoft even states in the KB article about the update that a problem in the Pre-Boot eXecution Environment (PXE) has been fixed. Quote from the KB article:

Fixes an issue that prevents the Pre-Boot eXecution Environment (PXE) from booting a device on a Windows Deployment Services (WDS) server for which the variable window extension is configured. This may cause the WDS server to disconnect prematurely when the image is downloaded. Clients or devices that do not use the variable window extension are not affected by this problem.

At the same time, some known issues are mentioned in the KB article, but PXE boot issues are not listed there.

A warning at Twitter

I don't use SCCM, but I became aware Twitter about the warning posted in the Tweet below.

Johan Arwidmark warns against distributing update KB4503276 dated June 11, 2019 to Deployment Points (DPs) of SCCM. It is highly likely that the PXE boot (for the Windows Deployment Service, WSD) will break during this process. If it all happens, since it's hard to debug because it occurs intermittently.  On  reddit.com is this thread from July 1, 2019, which also takes up the topic. Quote:


After June's CU applied to our DPs we have intermittent problems with PXE boot again. Looking at KB4503276 I can see that the old issue with variable window extension from the March CU is supposed to be solved.

I tried to set that value back to 0 since that was the recommended workaround in previous months and it appeared to initially solve the problem. But now we see about half of the PXE boots failing with the same error code as in March. All google results point to the registry value.

We have uninstalled the patch on one DP and are waiting for confirmation from other IT staff if PXE boot is working again or not.

We've also opened a ticket with MS about this but we've gotten nowhere so far. Does anyone else have these problems again after the June CU?

The problem is confirmed by other readers there. The worse thing is that even uninstalling the update does not solve the issue anymore. A user has posted a fix where he sets the option "Enable a PXE responder without Windows Deployment Services". See the reddit thread for more information.

Microsoft confirms the issue

I've had already written this post when I got another Twitter notification. The following tweet brought me to the right direction (thanks to (@PhantomofMobile for that).

Microsoft has released KB article 4512816 entitled 'Devices that start up using Preboot Execution Environment (PXE) images from Windows Deployment Services or System Center Configuration Manager may fail to start with error "0xc0000001"'. The issue affects virtually all versions of Windows Server that are still in support. Details can be found in the KB article, where a workaround is also discussed. Well, it's not my field of activity – but I assume that it will be helpful for those affected.

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One Response to June Update KB4503276 blocks PXE boot on SCCM DPs

  1. Pingback: KB4503276 may break sccm DP – Damberg Online

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