Obscure setting gives users more control over Windows auto-reboots

Windows has nasty habit of rebooting at worst moments. But new registry entry -- not mentioned by Microsoft -- lets users take control

Microsoft can't get rebooting right. In the early days of Windows XP, automatically applied security patches forced an immediate reboot. If you were gullible enough to turn on Windows Automatic Update or if your admin tossed an update down the pike over WSUS, you could come back from a coffee break and discover your work had disappeared.

Times have changed (a bit) for the better. Yesterday, as part of April's Black Tuesday, Microsoft released a patch that gives Windows 8 users a little more control over how and when Windows reboots. Too bad Microsoft forgot to mention that change in the patch's KB article.

When Microsoft first unleashed Automatic Updates, a security patch installation more often than not would automatically force a reboot. Just about every XP user I know has horror stories about leaving their PCs unattended for a few minutes or overnight and returning to discover all of their unsaved documents had been trashed, their browser sessions irretrievably lost, and/or massive copies or downloads summarily abandoned because of an auto-reboot.

Vista and Windows 7 learned some manners, but they too had a nasty habit of rebooting at the wrong time. Win7 puts a message on your screen inviting you to "Restart your computer to finish installing important updates." If you ignore the message or aren't around to handle it, the message keeps coming back periodically for up to four hours. After four hours, if you haven't responded to the message, Win7 throws in the towel and automatically restarts.

Nowadays, rebooting isn't as traumatic as it used to be. Most programs are smart enough to save backup copies of files, and all the major browsers can be resumed after a crash. That said, downloads and copying still die and they don't come back.

Responding to users' sustained screams of pain, Microsoft built Windows 8 to be very different -- infuriatingly so to some people. Here's how Microsoft puts it:

After you install an important update in Windows 8, you receive a notice that you have to restart the PC in three days. If the restart does not occur in three days, the PC displays a 15-minute countdown and then automatically restarts. By default, this automatic restart is delayed if the PC is locked, and the countdown will begin the next time that you sign in to the PC.

If your Win8 computer was locked when WSUS or Auto Update installed an "important" patch and stayed locked for more than three days, when you come back you have 15 minutes to deal with an impending but postponable reboot.

As part of yesterday's Black Tuesday patches, Microsoft released KB 2822241, a "Windows 8 and Windows Server 2012 cumulative update" rated "important." (Several Win8 Pro 64-bit users are reporting installation problems with this update.) Although the lengthy KB 2822241 article doesn't mention it, the patch also supports a new registry key that lets you modify the auto-reboot on a Windows 8 PC locked more than three days. Microsoft describes the new behavior in KB 2835627:

[The registry key] lets you force automatic restarts to finish installing important updates, regardless of whether you are at the PC... [When the key is changed], you are still notified of the upcoming automatic restart on the sign-in screen. However, at the end of the three-day period, the 15-minute counter begins even if the PC is locked. The restart also occurs even if the PC is locked.

If you set this key and are away from your Win8 PC for more than three days after an important update gets installed, Windows will just go ahead and automatically reboot.

Here's the registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU. You need to add a value called AlwaysAutoRebootAtScheduledTime with a Dword value of 1 to force a restart after three days. (0, the default, retains the old Win8 behavior.)

Registry old-timers might recall a similar setting that prevented XP, Vista, and Win7 from auto-rebooting as long as somebody's logged on to the computer. To override the four-hour time limit on those OSes, go to HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU and add a Value called NoAutoRebootWithLoggedOnUsers with a Dword value of 1.

Maybe in Windows 9 or Windows 10 we'll be able to choose how long to keep the reboot wolves at bay, but for now that's all she wrote.

Thanks to SB for the heads-up.

This story, "Obscure setting gives users more control over Windows auto-reboots," was originally published at InfoWorld.com. Get the first word on what the important tech news really means with the InfoWorld Tech Watch blog. For the latest developments in business technology news, follow InfoWorld.com on Twitter.