Blue screens and boot errors

Errors such as a repair loop, "no bootable device" or "inaccessible boot device" usually mean a start-up setting or an update is stuck. They're rarely a hardware fault. Try these fixes in order, from quickest to most thorough.

1. Quick fixes

1. Do a power drain (see My computer won't turn on) and restart.
2. Let updates finish. Leave the computer on and connected to the internet for an hour, then restart.
3. Note the stop code on the blue screen, for example WHEA_UNCORRECTABLE_ERROR, and take a photo.
4. Check the boot order. Enter the BIOS as the computer starts (F2 on Dell, F10 on HP, F1 or F2 on Lenovo). Choose Load defaults if you've changed anything, and make sure Windows Boot Manager is first. Save and exit.

2. Windows recovery tools

If Windows won't start after two or three tries, it opens the blue Choose an option screen. Select Troubleshoot > Advanced options, then:

• Startup Repair fixes most start-up problems automatically.
• Uninstall Updates removes a recent update that caused the problem.
• System Restore returns Windows to an earlier working point, if one exists.
• Startup Settings > Restart, then press 4, starts Windows in Safe Mode so you can remove a problem app or driver.

3. Reset this PC

If Windows still won't work properly, choose Troubleshoot > Reset this PC.

• Keep my files reinstalls Windows but keeps your documents. Apps are removed.
• Remove everything returns the computer to a fresh install.
• Choose Cloud download if asked. It downloads a fresh copy of Windows from Microsoft.

4. Clean reinstall of Windows from a USB

This erases everything on the computer and installs a fresh copy of Windows. Back up your files first, and use it when a reset hasn't worked.

You'll need: another working computer, a USB drive of at least 8 GB (it will be wiped), and an internet connection.

1. On the working computer, download the Media Creation Tool from Microsoft's Windows 11 download page.
2. Run it, accept the terms and choose Create installation media for another PC.
3. Choose your language and edition, select USB flash drive, and pick your USB drive. It takes 20 to 40 minutes.
4. Plug the USB into the computer you're fixing and turn it on while pressing the boot menu key: F12 on Dell and Lenovo, F9 on HP (press Esc first if needed). On a Surface, hold Volume down while pressing Power.
5. Choose the USB drive from the menu.
6. When Windows Setup opens, choose your language and select Install Windows 11.
7. At the product key screen, select I don't have a product key. Your digital licence activates Windows automatically once you're online.
8. Choose the same edition the computer had before (Home or Pro). Choosing a different edition stops it activating.
9. Select Custom: Install Windows only. Delete the partitions on the internal drive (Drive 0), select the unallocated space, and select Next.
10. When it restarts, remove the USB and complete setup (see First-time setup).

11. Install all Windows updates, then your maker's driver tool: Dell SupportAssist or Dell Command Update, HP Support Assistant, or Lenovo Vantage.
     

    Keep your computer running smoothly

• Install Windows updates as they arrive.
• Keep at least 25% of your C: drive free.
• Back up with OneDrive or an external drive.
• Give desktops 10 to 15 cm of space around their vents, and clear dust with compressed air, never a vacuum.