I run Matlab simulations that sometimes take weeks to finish and when Windows restarts I lose all my work so I really need a way to stop auto restarts.
Windows 11 seems to have disabled all ways to get around Auto Update Restarts. Is there a still a workaround?
It used to be possible to set NoAutoRebootWithLoggedOnUsers in:
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU
if you also set AUOptions to 4 in the same location but this does not work for me now.
Windows will not reboot during working hours. My solution is to run a scheduled task that changes the working hours in the registry, say every hour or two, so that it is never not a working hour. I coded up this 4 line cmd command batch file program:
for /f %%i in ('powershell "((get-date).Hour+18) %% 24"') do set startHour=%%i
for /f %%i in ('powershell "((get-date).Hour+12) %% 24"') do set endHour=%%i
reg add HKLM\SOFTWARE\Microsoft\WindowsUpdate\UX\Settings /v ActiveHoursStart /t REG_DWORD /d %startHour% /f
reg add HKLM\SOFTWARE\Microsoft\WindowsUpdate\UX\Settings /v ActiveHoursEnd /t REG_DWORD /d %endHour% /f
I then used Windows Task Scheduler to make this .bat script run every hour.
Tested: It works! I installed an update requiring a restart on 31-May. I am informed that this restart will happen outside of working hours. As of 20-June, 22 days later, no restart had taken place.
I figured out how to incorporate @Jonathan's feedback. It is easier to do modulo maths (and to get the hour independent of locale/region/format preferences) with powershell commands. It's still a cmd batch file, but it calls powershell. Reduces to 4 lines and should work everywhere.
$currentHour = (get-date).Hour; $startHour = ($currentHour+18) % 24; $endHour = ($currentHour+6) % 24
08 as an int to add. 2) Evil Windows Update has now started inserting Scheduled Tasks to wake up my PC and reboot it at the end of the active hours, so it won't stay asleep anymore!
08 is not GTR 5 for me, then it tries to run set /a startHour = 08+18 and fails with Invalid number error.
set /a 08 or set /a 09 to see. You always need to drop the leading zeros for it to work
Windows actually has an API that enables a process that has a window to block a system shutdown indefinitely until the user manually chooses what to do next. (possibly, as @josh3736 pointed out, Windows Update may break this eventually. But I personally have not experienced a concrete case of it. At least it should be safe to block a shutdown when you sleep until you wake up, and then you just click cancel to cancel the shutdown)
https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-shutdownblockreasoncreate
ShutdownBlockReasonCreatefunction (winuser.h)Indicates that the system cannot be shut down and sets a reason string to be displayed to the user if system shutdown is initiated.
Note that calling this alone cannot block a shutdown/restart successfully. You also need your application to handle the WM_QUERYENDSESSION and WM_ENDSESSION messages. I will discuss them at the end.
If you are not a developer so you do not know how to use Windows API, you can use a small program that I have written years ago for exactly the same purpose: https://github.com/real-guanyuming-he/ShutdownBlocker
Either way, when you have successfully created a shutdown block reason, Windows will pause when a shutdown (including an update restart) is issued, and display this to you, where you can click Cancel to cancel the shutdown.
Note: If you have no control over your Matlab simulations program (I do not use Matlab so I do not know if it is possible), then it might or might not work, depending on how Matlab handles the situation. According to Microsoft (https://learn.microsoft.com/en-us/windows/win32/shutdown/shutting-down),
Applications with a window and message queue receive shutdown notifications through the
WM_QUERYENDSESSIONandWM_ENDSESSIONmessages. These applications should return TRUE to indicate that they can be terminated.
If Matlab chooses to return TRUE on receiving this message, it will close, even if the shutdown is blocked this way. (And if you call the API without returning FALSE on receiving WM_QUERYENDSESSION, then it will not succeed as your app would close as a result of it)
ShutdownBlockReasonCreate simply sets the string that shows up in the shutdown UI (the one pictured in your screenshot); calling the method does not actually prevent shutdown from occurring. To prevent shutdown, you have to have an open window and return FALSE when you receive WM_QUERYENDSESSION. However, even if you do that, it's my impression that Windows Update gets aggressive and eventually forces a restart anyway, ignoring apps that try to prevent it.
FALSE on receiving WM_QUERYENDSESSION. I haven't been using it recently, but about one year ago, it could block an update that happened at midnight all the way until I woke up in the morning. Do not know if Microsoft will play some evil trick to force the restart continue anyway after a longer time.
Commented
May 28 at 10:45
WM_QUERYENDSESSION return value is the part that actually prevents shutdown. I'm just pointing out that ShutdownBlockReasonCreate is entirely informational, and contrary to what this answer says, calling it does not actually do anything to prevent a system shutdown.
WM_QUERYENDSESSION won't prevent a reboot indefinitely either. Eventually, Windows Update will force a restart anyway, which is why there's so much complaining about this on the internet.
The Group Policy Configure Automatic Updates allows you to prevent automatic installation of updates.
gpedit.mscSpecifies whether this computer will receive security updates and other important downloads through the Windows automatic updating service.
This setting lets you specify whether automatic updates are enabled on this computer. If the service is enabled, you must select one of the four options in the Group Policy Setting:
2 = Notify before downloading and installing any updates.
When Windows finds updates that apply to this computer, users will be notified that updates are ready to be downloaded. After going to Windows Update, users can download and install any available updates.
:-). By the way, for simulations that run for a long time it is common practice to dump the data and save the restart file every xx minutes, where xx is the amount of (simulation) time you are willing to lose. Usually we go by trial and error to translate the simulation time (MD) or the number of steps (MC) into human time...