Computer won't start after an update

A progress bar that sits still during an update is often still working. Apple’s startup page says that while macOS is installing, the Apple logo or progress bar can last much longer than a normal start, move slowly, and pause for long periods. The screen can go blank, then come back, several times. Leave the computer on power. On a laptop, leave the lid open. Apple’s update page says the Mac might restart and show a progress bar or a blank screen several times, and you should not put it to sleep or close the lid.

Force it off only when startup never gets past that screen. The repair tools below keep your files. Erase, Reset this PC with “remove everything,” and a firmware Restore delete them. The click-by-click version is Computer will not start after an update. If a later step wants to erase the disk and you have no other copy, stop and use Photos and files lost with no backup.

Photograph the screen, including any error code. Note what the update was called and the last time the screen changed. Unplug printers, external drives, docks, and USB hubs. Leave power connected. A wired keyboard helps if Bluetooth has not paired yet.

If it is a Mac

Apple’s progress-bar article gives this order when the Apple logo or the bar never advances.

1. Press and hold the power button for up to 10 seconds, until the Mac turns off. On a laptop with Touch ID, hold the Touch ID button down. A light touch is the fingerprint reader, not the power button.
2. Turn the Mac on. Give the installation the long wait again.
3. If it sticks in the same place, hold the power button until it turns off. Unplug nonessential accessories, then turn it on.
4. If it still sticks, shut it down the same way and start macOS Recovery. Repair the disk, then reinstall if the repair is not enough.

Apple recommends starting a major install in the evening so it can run overnight. A bar that moved once in the last hour is a reason to keep waiting. A bar that has not moved, after you have already power-cycled once and removed accessories, is the point where Recovery is the next step.

Open Recovery

The keys depend on the chip. Apple’s startup-keys page and the Apple silicon Recovery guide split it this way.

On a Mac with Apple silicon, shut down fully. The screen is black and the keyboard lights are off. Hold the power button until the startup disk and an Options button appear. Click Options, then Continue. If it asks, select a volume, select an administrator, and enter that password. A Bluetooth keyboard that will not pair can be set up by pressing the power button three times, about a second apart, on that startup screen.

On an Intel Mac, start up holding Command-R for the built-in Recovery system. That reinstalls the current version of the macOS you already had. Option-Command-R can install the latest macOS that Mac supports. Shift-Option-Command-R can install the macOS the Mac came with, or the closest version Apple still offers. Hold the keys together after the power button, not one at a time. A wireless keyboard is safer if you plug it in.

Repair the disk, then reinstall

In Recovery, open Disk Utility. Apple’s Apple silicon guide says to choose View, then Show All Devices. Run First Aid on each volume, then each container, then the storage device itself. Click Run, then Done, for each one. Quit Disk Utility when it finishes, and restart once.

If the Mac still will not start, go back to Recovery and reinstall. Apple’s reinstall page says this does not remove your apps or personal data, and a backup first is still the safer position if you can reach the files. Select Reinstall macOS, click Continue, and leave the lid open until it finishes. The Mac can restart and show an empty screen for minutes.

When it asks which disk, choose the current macOS disk. Apple says that is usually the only one, and if you see both “Macintosh HD” and “Macintosh HD - Data”, choose Macintosh HD. If the installer asks to unlock the disk, enter the password you use to log in to the Mac.

The installer needs a broadband connection that uses DHCP, over Wi-Fi or Ethernet. A cafe login page, an 802.1X network, or a PPPoE connection the router is not handling can block it. Use the Wi-Fi menu in Recovery to join a normal network.

Apple’s error page says a message about a damaged installer, a failed personalization, or not enough storage is sometimes temporary. Free space if the message says storage. Repair the disk before you download the installer again. If you were installing from Software Update rather than Recovery, safe mode can keep other software out of the way. From the Apple silicon startup screen, select the volume, hold Shift, and click Continue in Safe Mode.

When Recovery asks for a key

A FileVault recovery key is not your Apple Account password, and it is not an Apple Account recovery key. Apple’s password page says the FileVault key is 24 characters, created when FileVault was turned on. It does not include the letters I or S, or the numbers 1 or 0. Type it when Recovery or the login window asks for a recovery key.

If the Mac is on macOS Tahoe 26 or later, that key may be on another device. The other device has to be signed in to the same Apple Account, with iCloud Passwords & Keychain on. Open the Passwords app, search for “recovery key”, and open the item named for that Mac. Tap the dots in the Recovery Key field.

If you never saved a key and the login password will not unlock the disk, the reset steps on that same Apple page are the next place. Erasing the Mac permanently removes each user account and its data. Leave that until repair, reinstall, and password reset have failed.

Firmware revive

Apple’s error page says that rarely, a Mac with Apple silicon or a T2 chip needs a firmware revive or restore after an install failure. A power cut during installation is one of the cases Apple’s firmware page lists, along with an exclamation mark in a circle or a blank screen that the other blank-screen steps do not fix. Revive and restore both need a second Mac and a cable. Try Revive first. Apple says Revive does not erase the Mac. Restore erases it and returns it to factory settings. If Recovery itself will not open, that second-Mac path is the one to follow, and then Apple Support if the second Mac cannot see this one.

If the Mac reaches the desktop, back up before you run the update again. A full disk is a common reason the installer stops. Apple’s error page tells you to free storage when the message says there is not enough.

If it is Windows

Microsoft’s recovery page sorts this into two situations. If the PC starts but behaves badly, start with the lighter fixes. If it will not start, or it restarts in a loop, use the Windows Recovery Environment.

On Windows 11, version 24H2 or later, quick machine recovery can run by itself after repeated failed starts. Microsoft says it checks Windows Update for a fix, and it does not reset the PC or change your files, apps, or settings. It is on by default for Windows 11 Home. On Pro and Enterprise an administrator may have to turn it on. Restart once before you assume you must pick a tool. If no fix is waiting, the recovery screen is still there.

Windows 10 no longer gets free updates. Microsoft’s recovery environment page says support ended on October 14, 2025. The PC can still boot into recovery. The tools below are the ones Microsoft documents for Windows 10 and Windows 11.

Open the recovery tools

If Windows fails to start several times, it opens recovery on its own. You can force that. Microsoft’s steps:

1. Start the PC and wait for the Windows logo, or the maker’s logo.
2. As soon as the logo appears, hold the power button until the PC turns off.
3. Turn it on and do that a second time.
4. Turn it on a third time. You should see Automatic Repair.
5. Select Advanced options.

If you already made a USB recovery drive, start from that. On a working PC you can also make installation media and choose Repair my PC on the broken one. Changing the boot order, if the USB is ignored, is on the PC maker’s site.

BitLocker sits in front of most of these tools. Microsoft’s key page says the recovery key is 48 digits. Write down the first 8 digits of the key ID on the blue screen, so you can tell keys apart. From a phone, open aka.ms/myrecoverykey and sign in to the Microsoft account that turned encryption on. That might be a family member who set the PC up. From Windows 11, version 24H2, the recovery screen can show a hint of which Microsoft account holds the key.

A work or school PC may store the key in the organization. Open aka.ms/aadrecoverykey with that work account, or ask the IT desk. Microsoft Support cannot retrieve, provide, or recreate a lost key. If you cannot find it, Microsoft says the remaining path is a reset, and a reset removes your files.

Which tool keeps your files

Use them in this order when the failure started with an update. Microsoft’s comparison is the source for what each one deletes.

1. Startup Repair. In recovery, select Troubleshoot, Advanced options, Startup Repair, then Restart. Microsoft’s Startup Repair page says it tries to fix damaged startup files, boot configuration, and some driver problems. It needs the BitLocker key if the drive is encrypted.
2. Uninstall updates. Select Troubleshoot, Advanced options, Uninstall Updates. Microsoft’s uninstall page says to pick Uninstall latest quality update. Your files and apps stay. Some updates cannot be removed. Microsoft also says that before you remove a security update you should understand the risk, and that on Windows 11 you should try reinstalling the current version first when you can get into Windows. That reinstall, from a PC that starts, keeps files, apps, and settings. When the PC will not start, the recovery uninstall is the path Microsoft lists second, after point-in-time restore on version 24H2.
3. Point-in-time restore, only on Windows 11 version 24H2 or later. Select Troubleshoot, then Point-in-time restore. This rolls the whole PC back, including personal files, apps, and settings, to an automatic point. Microsoft says those points go back up to 3 days. Changes after the point are lost. Files already in OneDrive or another cloud service are left as they are. Read that twice if you saved work only on the PC since the point.
4. System Restore, if you need a point older than those 3 days, or point-in-time restore is missing. It rolls back system files and settings. Personal files stay. Recently installed apps and drivers can disappear.
5. Reset this PC. Select Troubleshoot, then Reset this PC. You choose whether to keep personal files. Apps and settings are removed either way. Try the earlier tools first.
6. Cloud rebuild, on Windows 11. Select Troubleshoot, then Cloud rebuild. Microsoft says this removes personal files, apps, and settings. Cloud copies are not removed. A local-only photo library is.

Going back to the previous Windows version, if the PC starts, is available for 10 days after an upgrade. Personal files stay. Apps, drivers, and settings added after the upgrade are removed.

A recovery drive is for reinstalling Windows. Microsoft says that reinstall removes personal files, apps, and settings. Installation media from the Windows download page needs a USB drive of at least 8 GB, made on another PC. Depending on the choices in setup, you can keep personal files and apps, keep personal files only, or keep nothing. Read the screen before you confirm.

If the failure is one Windows PC and a phone still works on the same Wi-Fi, the update is the likely cause. If every device in the house is offline, fix the connection with Home internet not working before you reset Windows. Recovery can need the network for a cloud fix.

After it starts

Reach the desktop, restart once more, and confirm you get there again. Open a document and a photo. Then copy them somewhere other than this disk before you retry the update. The FileVault key or the BitLocker key has to be readable from a phone or a piece of paper, because the broken computer cannot show it to you.

If Recovery cannot see the disk, or Disk Utility cannot repair it, Apple says the Mac may need service. The same is true if Windows recovery cannot unlock the drive and you do not have the BitLocker key. Stop there. A shop can image a disk that still spins. An erase cannot be undone.

The full order, including what to save before the next update, is in Computer will not start after an update. If the disk is the only copy of the files and a step now says erase, switch to Photos and files lost with no backup before you click it.

Related playbooks

• Computer will not start after an update. A Windows or macOS update leaves the computer stuck, restarting, or unable to reach the desktop.
• Photos and files lost with no backup. The drive died, the phone went in the water, or the folder is simply gone, and there was never a copy.