Computer Updates and Restarts (Reboots)
Your work computer gets security updates every month, and most of them need a restart to finish. This page explains when that happens, what the restart prompt looks like, why it sometimes asks more than once, and why urgent security fixes can come on any day.
The short version
- Monthly updates: planned restarts begin on the 25th of every month, whatever day of the week that is.
- Urgent security fixes: can come on any day, and sometimes during working hours. Why?
- The prompt: a box titled System Notification appears on your screen. See it
- Asked again? Restart again. Some updates need two or three restarts to finish. Why?
- What to do: save your work, close your apps and click Restart now.
When Updates and Restarts Happen
We schedule updates centrally. We don't leave Windows to restart whenever it feels like it.
- Microsoft releases its regular monthly fixes on the second Tuesday of each month. We test them first, and then planned restarts begin on the 25th of every month, regardless of the day of the week.
- The 25th is the start of the window, not a promise that every computer restarts at 9:00 a.m. that morning.
- If your computer is off or offline (a laptop closed in a bag, or a desktop that was powered off), nothing is missed. The next time it's on and connected, the updates finish installing, and then you're asked to restart.
The one exception is urgent security fixes, below.
Urgent Security Updates: Any Day, Sometimes During Work Hours
Some security problems can't wait for the 25th. When a fix for a dangerous security flaw comes out, we may install it as soon as we've validated it, on any day of the month.
How quickly depends on how severe the flaw is and whether attackers are already using it. For the most serious ones, the update and its restart prompt may be sent during your workday instead of waiting for the evening or the 25th. A restart in the middle of the day is an interruption, but leaving a known hole open to attackers is the bigger risk.
What makes a security update urgent? You may hear these terms in the news or from us:
- Zero-day: a flaw that attackers know about, and may already be using, before the software maker has a fix ready. The name comes from the maker having had "zero days" to fix it.
- Actively exploited: criminals are using the flaw in real attacks right now, not just in theory.
- High or Critical CVE: publicly known security flaws get an ID called a CVE (it looks like CVE-year-number) and a severity score from 0 to 10. A score of 7.0 to 8.9 is High, and 9.0 to 10 is Critical. The worst can let an attacker run their own programs on a computer or get at its data, sometimes without anyone clicking anything.
What the Restart Prompt Looks Like
You'll see a box on your screen titled System Notification. It isn't an email, and it isn't a browser pop-up.
Typical wording:
- Heading: Reboot required for system updates
- Message: In order to apply security patches and system updates, your computer must be restarted. Please save all work, close all applications and select 'Yes' to restart your computer.
- Buttons: Remind me later or Restart now
The message says to select "Yes," but the button to click is Restart now.
If You Click Remind Me Later
You can put it off briefly while you finish and save what you're doing, but not forever.
| Setting | What you will see |
|---|---|
| How often it asks again | About every 1.5 to 2 hours until you restart |
| How many reminders | 2 to 3 prompts, depending on how urgent the update is. The box may show how many are left. |
| If you keep postponing | The last prompt stays on screen for 3 to 5 minutes, then the computer restarts so the updates can finish |
If nobody is signed in, or nobody has used the mouse or keyboard for more than 5 minutes, the computer restarts on its own. That's why a computer that restarted overnight around the 25th was usually just doing maintenance.
Asked to Restart Again? Restart Again.
Most months, one restart finishes the job. Some months the prompt comes back. That's not a glitch, and your computer isn't "stuck." Windows is finishing the next layer of updates, which it couldn't start until the first restart was done.
After the first restart, you might see:
- "Working on updates" or "Configuring Windows" on a blue or black screen
- The same System Notification box a little later
- A second Restart now after you've already restarted once today
Restart again. That's how the rest of the updates finish. Closing the box or ignoring it delays your security fixes and can leave the computer half-updated until the next forced restart.
Two (occasionally three) restarts in the same update cycle, with this same box, are normal. That's different from a computer that keeps restarting for days, or restarts with no prompt at all (see When to Contact Us).
Think of it like painting a room. The primer has to dry before the next coat goes on. The first restart lets the first coat finish, and the second restart lets the next coat go on. Skipping it leaves the job half-done, and half-installed security updates are exactly what we're trying to avoid.
The technical reason Windows can need more than one restart
Windows doesn't install "one big update." A monthly cycle is usually a stack of smaller pieces that have to go on in order:
- Some updates have to go first. Others depend on them, such as updates to Windows' own update installer (the "servicing stack"), and can't install until the first ones are in place, which sometimes takes a restart.
- Some files are in use while you work. Core Windows files, including the kernel and drivers, can't be replaced while they're running. A restart is when Windows swaps them.
- Some pieces wait their turn. After the first restart, Windows keeps "configuring updates." It may then install .NET, another security package, or a component that was waiting on that first swap, and those can need a second restart.
Two (occasionally three) planned restarts in one cycle means the updates are going on in the safe order, not that something is broken.
What You Don't Need to Do
- Don't click Check for updates in Windows Settings to "hurry it along," even when you hear about an urgent flaw in the news. That can pull in updates we haven't finished testing, and urgent fixes reach you from us automatically. See Windows Updates on Managed Computers.
- Don't download a "reboot fixer" or extra update tool from the web.
- Don't assume two restarts mean ransomware or a crash. Look at the prompt. If it's the System Notification restart box, it's maintenance.
When to Contact Us
- The computer restarts while you're actively working without notice, with no chance to save
- It keeps restarting days later, or restarts without the System Notification "Reboot required" box, after this month's updates should already be done
- You see a full-screen crash or stop code instead of this box
- The computer never comes back to the sign-in screen
Related Articles
- Windows Updates on Managed Computers: why "Last checked" looks old, and how updates are scheduled
- Why did my computer restart?: scheduled restart, crash, power or heat
- Rebooting/Restarting your Computer: Restart, not Shut down
- Recovering a deleted file or an earlier version: if a restart cost you an unsaved file