nathans :ms_weed:<p>October Windows Server updates cause Hyper-V VM boot issues</p><p>According to customer reports, this month's Patch Tuesday updates are breaking virtual machines on Hyper-V hosts, causing them to no longer boot and display "failed to start" errors.</p><p>According to complaints from Windows admins, the issue is triggered after installing KB5031361 and KB5031364 on Windows Server 2019 and Windows Server 2022 systems.</p><p>A Microsoft spokesperson told BleepingComputer that the company is aware of the issue and is investigating.</p><p>The following errors will be logged to the event viewer when trying to start a VM on an affected Hyper-V system:</p><p> Failed to start virtual machine TOOLS. Error: 'TOOLS' failed to start.<br> Failed to Power on with Error 'Incorrect function.'<br> Failed to open attachment 'vhdx_path'. Error: 'Incorrect function.'</p><p>Administrators with impacted devices have noted that uninstalling the problematic updates resolves the issue, allowing all virtual machines (VMs) to start up without any problems.</p><p><a href="https://infosec.exchange/tags/Microsoft" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Microsoft</span></a> <a href="https://infosec.exchange/tags/WindowsServer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>WindowsServer</span></a> <a href="https://infosec.exchange/tags/Server" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Server</span></a> <a href="https://infosec.exchange/tags/News" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>News</span></a> <a href="https://infosec.exchange/tags/HyperV" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>HyperV</span></a> <a href="https://infosec.exchange/tags/PatchTuesday" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>PatchTuesday</span></a> <a href="https://infosec.exchange/tags/InfoSec" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>InfoSec</span></a> </p><p><a href="https://www.bleepingcomputer.com/news/microsoft/october-windows-server-updates-cause-hyper-v-vm-boot-issues/" rel="nofollow noopener noreferrer" translate="no" target="_blank"><span class="invisible">https://www.</span><span class="ellipsis">bleepingcomputer.com/news/micr</span><span class="invisible">osoft/october-windows-server-updates-cause-hyper-v-vm-boot-issues/</span></a></p>