How to Fix GRUB Missing or Windows 11 Booting Straight to Windows After an Update on a Dual-Boot Linux PC

Your GRUB menu is missing after a Windows 11 update, and your dual-boot PC now boots straight into Windows with no option to pick Linux. Your Linux install and files are almost always still there. Community troubleshooting reports suggest that these updates typically change only the firmware boot order or the boot entry that points to GRUB, rather than touching your Linux partition, though this isn’t officially documented by Microsoft.

Fix #1: Check Whether GRUB Is Missing or Just Skipped After the Windows 11 Update

Before you touch any disk, find out which of two problems you have. They look identical at startup, but the fixes are very different:

• Boot-order change: The Linux entry (usually labeled “ubuntu”) still exists in your firmware. Windows Boot Manager has simply been moved ahead of it. This takes about five minutes to fix.
• Missing boot entry: The “ubuntu” entry is gone from the firmware, or the GRUB files on the EFI System Partition are damaged. You’ll need an Ubuntu live USB to repair it.

Here’s a quick map of which fix matches which symptom:

Symptom	Likely Cause	Go To
PC boots to Windows, but “ubuntu” shows up in the one-time boot menu	Boot order changed	Fix #2 and Fix #3
“ubuntu” is missing from the boot menu entirely	Firmware entry removed or GRUB files damaged	Fix #4 or Fix #6
GRUB reinstalled, but the PC still skips it	Entry not first in boot order, or entry not recreated	Fix #3 and Fix #5
GRUB menu appears, but Windows isn’t listed	OS detection off, or the Windows partition can’t be read	Fix #7
Linux entry exists but won’t start, or shows a security error	Secure Boot or legacy/CSM mode mismatch	Fix #8

Use the one-time boot menu to tell the two cases apart:

• Fully shut down the PC. Don’t just pick Restart.
• Power it on and start tapping your manufacturer’s one-time boot menu key right away. Common keys include F12, F11, F10, F2, Esc, and Delete, but they vary by brand and model. Check the logo screen during startup or your PC’s manual for the correct key.
• Look at the list of boot entries. You should see Windows Boot Manager. Check whether an entry named ubuntu (or your distro’s name) also appears.

If you can’t catch the key in time, you can reach the firmware from inside Windows 11:

• Open Settings > System > Recovery.
• Next to Advanced startup, click Restart now.
• Choose Troubleshoot > Advanced options > UEFI Firmware Settings > Restart.

This opens the full firmware setup screen rather than the one-time menu. The boot order list there shows the same entries.

What the result means: If “ubuntu” is listed, go to Fix #2. If it isn’t, your Linux partition is still very likely intact. Skip to Fix #4.

Before any repair that writes to disk: Back up anything important from Windows to an external drive. A portable SSD like the Samsung T7 or any external hard drive works fine. If BitLocker is on, make sure you have your recovery key, because firmware changes can trigger a BitLocker recovery prompt.

Fix #2: Boot Ubuntu From the One-Time Menu and Run update-grub

Use this fix if “ubuntu” appeared in the boot menu in Fix #1.

Symptoms:

• The PC goes straight to Windows 11 after a Windows Update.
• Selecting “ubuntu” from the one-time boot menu starts Linux normally.

Why it happens: The update moved Windows Boot Manager to the top of the firmware boot order. Your Linux entry and GRUB are fine. The firmware just isn’t trying them first.

Steps:

• Open the one-time boot menu again (see Fix #1).
• Select ubuntu and press Enter.
• If the GRUB menu appears, choose your normal Ubuntu entry and log in.
• Open a terminal with Ctrl + Alt + T.
• Run sudo update-grub and enter your password.
• Read the output. You should see lines listing the Linux kernels it found. If Windows is detected, you’ll see a line mentioning Windows Boot Manager.

sudo update-grub

Verify it worked: Reboot and pick “ubuntu” from the one-time menu again. The GRUB menu should list both Ubuntu and Windows Boot Manager. If the PC still boots straight to Windows when you don’t use the one-time menu, continue to Fix #3. That’s normal at this stage.

Fix #3: Move the ubuntu Entry Above Windows Boot Manager in UEFI Boot Order

The one-time menu is only a one-time override. To stop the PC from going straight to Windows every time, change the permanent boot order.

Symptoms:

• Linux boots when you select it manually.
• Every normal startup goes straight to Windows 11.

Why it happens: The firmware’s boot priority list now has Windows Boot Manager first. Community reports link this to Windows Updates changing the boot order, though Microsoft doesn’t document this as an expected behavior.

Steps:

• Enter the full UEFI firmware setup. Use the setup key for your PC, often F2 or Delete, or use Settings > System > Recovery > Advanced startup from Fix #1.
• Find the boot section. Depending on your manufacturer, it may be called Boot, Boot Order, Boot Priority, Boot Sequence, or UEFI Boot Order.
• Select ubuntu and move it to the top of the list. Firmware uses different controls for this, such as +/- keys, F5/F6, arrow keys, or dragging with a mouse. On-screen hints usually tell you which.
• Leave Windows Boot Manager in the list, below ubuntu. Don’t delete it. GRUB hands off to it when you choose Windows.
• Save and exit, usually with F10 or a Save & Exit option.

Verify it worked: Restart without pressing any keys. The GRUB menu should appear. If the order reverts to Windows after a later update, repeat this fix or use the efibootmgr method in Fix #5.

Tip: Some firmware has a “boot from Windows Boot Manager first” or similar option that puts Windows back on top. If your order keeps reverting by itself, look for a setting like that in the boot section.

Fix #4: Reinstall GRUB From an Ubuntu Live USB (chroot Method)

Use this fix if “ubuntu” was missing from the boot menu in Fix #1. You’ll boot a temporary Ubuntu from a USB stick, “step into” your installed Linux, and reinstall GRUB. You don’t need to reinstall Ubuntu.

Symptoms:

• No Linux entry appears anywhere in the one-time menu or the firmware boot order.
• The PC only boots Windows 11.

Why it happens: The firmware entry for Linux was overwritten or removed, or the GRUB files on the EFI System Partition (ESP) were damaged. The ESP is a small partition that holds bootloaders for both Windows and Linux.

Prepare the live USB

• On a working PC, download an Ubuntu ISO and write it to a USB flash drive sized to comfortably fit the ISO you download, since image sizes vary by release. Ideally, use the same Ubuntu release you have installed. Check Ubuntu’s release cycle page to see which releases are still supported, and check the current download page for the recommended USB capacity.
• Plug the USB drive into the broken PC and open the one-time boot menu.
• Choose the USB entry that starts with UEFI, if you see both a UEFI and a non-UEFI option. The live USB must boot in UEFI mode, not legacy/CSM, or GRUB will install the wrong way.
• When Ubuntu loads, choose the option to try Ubuntu without installing. The wording varies by release.

Identify your partitions safely

This is the step that keeps you from writing to the wrong disk. Take your time.

• Open a terminal with Ctrl + Alt + T.
• Confirm the live session booted in UEFI mode:

ls /sys/firmware/efi

If you get “No such file or directory,” you booted in legacy mode. Reboot and pick the UEFI USB entry.

• List all partitions with their filesystems and labels:

lsblk -f

• Find the EFI System Partition. It’s formatted vfat, it’s small (usually a few hundred MB), and it’s on the same disk as Windows and Linux.
• Find your Linux root partition. On a standard Ubuntu install it’s usually ext4 and much larger. The ntfs partitions belong to Windows. Leave them alone.
• For a second check, run sudo fdisk -l. The ESP is listed with the type EFI System.
• Write down both device names. In the examples below, the ESP is /dev/nvme0n1p1 and the Linux root is /dev/nvme0n1p5. These are examples only. SATA drives use names like /dev/sda1, and your partition numbers will likely differ.

Seeing your Linux partition in lsblk -f confirms the partition itself still exists, which is a good sign. It doesn’t guarantee every file or the installation’s bootability is intact, but a missing partition would be a much bigger problem than what this guide covers.

Encrypted install? If your Linux partition shows as crypto_LUKS, it must be unlocked before you can mount it. The steps get more involved, so consider Boot-Repair (Fix #6) or the community resources under “Getting Help.”

Mount, chroot, and reinstall GRUB

• Mount your Linux root partition. Replace the device name with yours:

sudo mount /dev/nvme0n1p5 /mnt

• If you set up a separate /boot partition during install, mount it next with sudo mount /dev/YOUR-BOOT-PARTITION /mnt/boot. Most default installs don’t have one.
• Mount the EFI System Partition:

sudo mount /dev/nvme0n1p1 /mnt/boot/efi

• Bind-mount the system directories GRUB needs. /dev, /proc, and /sys alone are sometimes enough for grub-install to write files, but /dev/pts, /run, and access to efivarfs are commonly needed too, especially for efibootmgr to register a new NVRAM boot entry:

sudo mount --bind /dev /mnt/dev
sudo mount --bind /dev/pts /mnt/dev/pts
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys
sudo mount --bind /run /mnt/run
sudo mount -t efivarfs efivarfs /mnt/sys/firmware/efi/efivars

If that last command fails with an error about efivarfs already being mounted or not supported, double check you booted the live USB in UEFI mode (see “Identify your partitions safely” above). Skipping this mount can let grub-install finish without actually creating the “ubuntu” entry in the firmware boot order.

• Enter your installed system:

sudo chroot /mnt

Your prompt changes. You’re now working inside your installed Ubuntu, as root.

• If you suspect the EFI boot files themselves are damaged, rather than just missing a firmware entry, reinstall the signed boot packages for your architecture before touching GRUB. Check your architecture first, then reinstall:

dpkg --print-architecture
sudo apt update
sudo apt install --reinstall grub-efi-amd64-signed shim-signed

Use grub-efi-arm64-signed instead of the amd64 package on ARM64 installs, or grub-efi-ia32 on 32-bit UEFI firmware; shim-signed generally doesn’t apply outside x86_64. Package names and availability vary by Ubuntu release, so check apt search grub-efi inside the chroot if the install command reports a missing package.

• Reinstall GRUB to the EFI System Partition. Specify the target, EFI directory, and bootloader ID explicitly so GRUB writes to the right location and attempts to register the firmware entry, substituting arm64-efi or i386-efi for --target if your install uses a different architecture:

grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=ubuntu

Running grub-install with no options can also work, since it tries to detect these values automatically, but the explicit flags above are the more reliable choice for this repair. Check the output for errors either way, and run grub-install --help inside the chroot if you need to confirm which options your release supports.

• Regenerate the GRUB menu:

update-grub

• Leave the chroot, unmount everything, and reboot:

exit
sudo umount -R /mnt
sudo reboot

If umount -R reports that a target is busy, close any file managers or terminals still using /mnt and try again. You can also just reboot anyway, since a live session discards its own state either way.

• Remove the USB drive when prompted.

Verify it worked: Open the one-time boot menu. “ubuntu” should be back. If it’s there but the PC still skips GRUB, do Fix #3. If “ubuntu” still doesn’t appear even though grub-install reported no errors, the files were written but no NVRAM entry was created; go to Fix #5 and use efibootmgr to add one manually.

This chroot sequence is standard community practice. Ubuntu doesn’t publish it word for word on a single official page, so compare it with current Ubuntu documentation if your release behaves differently.

Fix #5: Recreate the Linux Boot Entry With efibootmgr (or Reorder It With bcdedit)

grub-install normally registers the “ubuntu” firmware entry itself. If it didn’t, or if your firmware keeps losing it, you can add or reorder the entry manually.

• efibootmgr is a Linux tool that reads and edits your firmware’s boot entries.
• bcdedit is the Windows equivalent. It can view and reorder firmware entries, but it can’t reinstall GRUB.

You only need these tools if Fixes #3 and #4 didn’t leave a working “ubuntu” entry at the top of the boot order.

From Linux with efibootmgr

Run these from your booted Ubuntu, or from inside the chroot in Fix #4.

• List the current firmware entries:

sudo efibootmgr -v

• Note the four-digit number for each entry (for example, Boot0000 for Windows Boot Manager) and the current BootOrder.
• Confirm the Ubuntu loader files exist on the ESP:

ls /boot/efi/EFI/ubuntu

You should see shimx64.efi (used with Secure Boot) and grubx64.efi.

• If no “ubuntu” entry exists, create one. Point --disk at the whole disk, not the partition, and --part at the ESP’s partition number:

sudo efibootmgr --create --disk /dev/nvme0n1 --part 1 --loader '\EFI\ubuntu\shimx64.efi' --label "ubuntu"

• Set the boot order so the new entry comes first and Windows comes second. Use your own entry numbers from step 1:

sudo efibootmgr -o 0003,0000

Flags can vary between efibootmgr versions, so check man efibootmgr before running the create command. Never use the delete options (-B) on the Windows Boot Manager entry.

Verify it worked: Run sudo efibootmgr -v again. “ubuntu” should be listed and appear first in BootOrder.

From Windows with bcdedit

If you can only get into Windows, you can still check the firmware entries and move an existing “ubuntu” entry up.

• Right-click Start and choose Terminal (Admin).
• List firmware entries:

bcdedit /enum firmware

This is meant to list UEFI firmware boot entries, including any existing Linux entry, but the exact output format can vary by Windows version and firmware.

• Find the entry whose description is ubuntu and copy its identifier, the GUID in curly braces.
• Move it to the top of the firmware boot order:

bcdedit /set "{fwbootmgr}" displayorder "{YOUR-UBUNTU-GUID}" /addfirst

Microsoft’s documentation doesn’t spell out this exact firmware-reorder use case, so verify the syntax with bcdedit /? on your system before relying on it. Treat it as a workaround rather than a guaranteed fix, since firmware and BCD behavior can differ across PCs.

If no “ubuntu” entry appears in step 2, bcdedit can’t help. Go back to Fix #4.

Fix #6: Use Boot-Repair if You’d Rather Not Type Commands

Boot-Repair is a free graphical tool from the Ubuntu community. It automates most of what Fixes #4 and #5 do by hand. You get less control over which partition is touched, but much less typing.

• Boot the Ubuntu live USB in UEFI mode, as in Fix #4. If your installed Ubuntu still boots, you can use that instead.
• Connect to the internet.
• Install Boot-Repair. At the time of writing, the project distributes it through a PPA. Check the project’s current instructions first, since the install method can change:

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt update
sudo apt install -y boot-repair

• Launch it by searching Boot-Repair in the app menu, or by running boot-repair in a terminal.
• Wait for the scan to finish, then click Recommended repair.

• Follow any on-screen prompts. Some ask you to copy and paste commands into a terminal.
• If Boot-Repair shows a summary report or link at the end, save it. It’s useful if you need to ask for help.
• Reboot and remove the USB drive.

Verify it worked: Check the one-time boot menu for “ubuntu,” then confirm the GRUB menu appears on a normal startup. If it doesn’t, apply Fix #3.

Fix #7: Get Windows Back Into the GRUB Menu

Symptoms:

• GRUB loads fine after the repair.
• The menu lists only Ubuntu entries. Windows Boot Manager is missing.

Why it happens: update-grub didn’t detect Windows. Community troubleshooting commonly points to these causes, though they aren’t confirmed in official Microsoft or Ubuntu documentation:

• BitLocker encryption
• Windows Fast Startup leaving the disk in a hibernated state
• The disk running in Intel RST/RAID mode instead of AHCI
• OS detection being turned off in GRUB’s settings

Steps:

• Boot Ubuntu and run sudo update-grub again. Check whether a “Found Windows Boot Manager” line appears.
• If it doesn’t, open GRUB’s settings file with sudo nano /etc/default/grub.
• Look for a line reading GRUB_DISABLE_OS_PROBER. On some newer releases, GRUB doesn’t scan for other operating systems unless this is set to false. If the line is missing or commented out with #, add or change it to GRUB_DISABLE_OS_PROBER=false.
• Save the file with Ctrl + O, press Enter, then exit with Ctrl + X.
• Run sudo update-grub again.
• If Windows still doesn’t appear, boot into Windows and turn off Fast Startup. Go to Control Panel > Hardware and Sound > Power Options > Choose what the power buttons do, click Change settings that are currently unavailable, and clear Turn on fast startup.

• Check BitLocker status from Terminal (Admin) with manage-bde -status.
• Shut Windows down fully, boot Linux, and run sudo update-grub once more.

Even without a GRUB entry, you can always reach Windows by picking Windows Boot Manager from the one-time boot menu.

Verify it worked: Reboot. The GRUB menu should list Windows Boot Manager, and selecting it should start Windows 11.

Changing your disk controller from RAID/RST to AHCI in firmware can stop Windows from booting if you do it carelessly. Only attempt it with a backup and a guide written for your exact PC model.

Fix #8: Check Secure Boot and UEFI Mode

Symptoms:

• The “ubuntu” entry exists but won’t start.
• You get a security violation message, or the PC drops back to Windows.

Why it happens: Secure Boot only runs signed bootloaders. Ubuntu ships a Microsoft-signed shim and a Canonical-signed GRUB designed to work with Secure Boot enabled, according to Ubuntu’s Secure Boot documentation (retrieved November 5, 2026). Problems usually come from booting the wrong loader or mixing UEFI and legacy modes.

Steps:

• In firmware setup, confirm the PC boots in UEFI mode and that CSM / Legacy boot is off. The labels vary by manufacturer.
• Make sure your boot entry points to shimx64.efi, not grubx64.efi, when Secure Boot is on. You can check this with sudo efibootmgr -v (see Fix #5).
• Don’t replace Ubuntu’s signed boot files with unsigned custom builds.
• If you need to rule Secure Boot out, disable it temporarily for one test boot, then turn it back on. Expect a BitLocker recovery prompt in Windows if BitLocker is enabled.

Verify it worked: With Secure Boot back on, the “ubuntu” entry should load GRUB without errors.

Error Messages Quick Reference

Message or Screen	What It Means	Fix
PC boots straight to Windows 11, no menu	Boot order changed or Linux entry removed	Fix #1, then #2–#4
grub rescue> prompt	GRUB started but can’t find its files	Fix #4 or Fix #6
“Minimal BASH-like line editing is supported”	GRUB shell loaded without a working config	Fix #4 (update-grub)
“error: no such partition”	GRUB is looking for a partition that moved or changed	Fix #4
“EFI variables are not supported on this system”	Live USB booted in legacy/CSM mode	Reboot the USB in UEFI mode (Fix #4)
“cannot find EFI directory” (from grub-install)	ESP not mounted at /boot/efi inside the chroot	Remount the ESP (Fix #4)
“Installation finished. No error reported.”	grub-install succeeded	Run update-grub, then reboot
“Verification failed: (0x1A) Security Violation”	Secure Boot rejected a boot component	Fix #8
BitLocker recovery screen after firmware changes	Boot configuration change triggered BitLocker	Enter your recovery key, then continue

Platform-Specific Notes

Windows 11 side

Major Windows 11 feature updates are a common trigger, which you can verify in the Windows 11 Settings app. You can see which updates installed recently under Settings > Windows Update > Update history. Microsoft’s Windows 11 release information page lists current versions and builds. Expect to recheck your boot order after big feature updates.

Firmware differences

Every PC maker labels these screens differently. The one-time boot menu key, the setup key, and names like “Boot Priority” or “UEFI Boot Order” all vary. If the keys listed here don’t work, check the startup splash screen or your PC’s support page. You can always fall back on Settings > System > Recovery > Advanced startup.

Configuration Mistakes to Avoid

• Wrong: Running sudo mount /dev/nvme0n1p3 /mnt because “p3 looked right.”

Right: Run lsblk -f first and confirm the filesystem type and size before every mount.

• Wrong: Booting the live USB from a non-UEFI entry.

Right: Pick the UEFI: USB entry and confirm with ls /sys/firmware/efi.

• Wrong: Mounting the ESP at /mnt/boot or forgetting it entirely.

Right: Mount the ESP at /mnt/boot/efi before you chroot.

• Wrong: Passing the partition to efibootmgr --disk, as in /dev/nvme0n1p1.

Right: Pass the whole disk (/dev/nvme0n1) to --disk and the partition number (1) to --part.

• Wrong: Deleting Windows Boot Manager so “Linux wins.”

Right: Keep Windows Boot Manager in the list and move ubuntu above it.

• Wrong: Reinstalling Ubuntu as a first resort.

Right: Work through Fixes #1–#6 first. A partition that still shows in lsblk -f is a good sign your data survived, but confirm you can actually mount and read it before ruling out a reinstall.

Getting Help

If you’re still stuck, collect this information before posting on Ask Ubuntu or Ubuntu Discourse:

• Output of lsblk -f and sudo fdisk -l from the live USB
• Output of sudo efibootmgr -v
• Contents of /etc/default/grub
• The full text of any grub-install or update-grub errors
• Output of bcdedit /enum firmware and manage-bde -status from an admin terminal in Windows
• The Boot-Repair summary report, if it produced one
• Your PC model and Ubuntu release

Remove anything personal, such as your BitLocker recovery key, before sharing output publicly.

Prevention Tips

• Check the boot order after big updates: A quick look at the firmware boot list after a Windows 11 feature update catches problems before they surprise you.
• Keep a live USB handy: A spare USB flash drive with your current Ubuntu release turns a scary evening into a 15-minute repair.
• Leave Fast Startup off: It helps Linux read the Windows partition and keeps GRUB’s Windows detection more reliable.
• Back up both systems: An external SSD with recent copies of your Windows and Linux files makes any disk-level fix far less stressful.
• Save your BitLocker recovery key: Firmware and Secure Boot changes can trigger a recovery prompt.
• Revisit your setup: If you ever rebuild the dual boot, our dual-boot Ubuntu and Windows 11 guide covers installation and partitioning.

Help & Answers

Frequently Asked Questions

4 questions

Did the Windows Update delete my Linux installation?

Almost certainly not. In this scenario, only the boot configuration changes: either the firmware boot order or the boot entry that points to GRUB. Your Linux partition and files are normally untouched.

If the partition appears in lsblk -f from a live USB, that’s a strong sign it’s intact, though you should still confirm it mounts and reads correctly.

Why does my PC boot straight to Windows with no GRUB menu?

The firmware is loading Windows Boot Manager first. Either the update moved it to the top of the boot order (Fix #3), or the Linux entry is gone (Fix #4).

Do I need efibootmgr or bcdedit?

Usually not. grub-install normally creates the firmware entry, and firmware setup handles the boot order. Use efibootmgr or bcdedit only if the entry won’t stick or won’t appear.

Is there an easier way than typing commands?

Yes. Boot-Repair (Fix #6) automates the repair through a graphical window. You’ll still need the live USB and a few install commands.

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Wrapping Up

In many dual-boot cases, this is a firmware boot-order or NVRAM entry problem. Fix #2 and Fix #3 (pick “ubuntu” once, then move it above Windows Boot Manager) get people back to GRUB in a few minutes without touching Linux.

If the entry is truly gone, the live USB chroot repair in Fix #4 is the most reliable path, and Boot-Repair is a solid backup if you’d rather click than type. If GRUB keeps vanishing even when no update has run, or your Linux partition stops showing up in lsblk -f, suspect a failing drive and back up your data before anything else.

Step	Action	Applies To
1	Check the one-time boot menu for “ubuntu”	Everyone
2	Boot ubuntu and run sudo update-grub	Entry still present
3	Move ubuntu above Windows Boot Manager	Entry present, PC keeps reverting
4	Live USB chroot, grub-install, update-grub	Entry missing
5	Recreate or reorder the entry with efibootmgr/bcdedit	Entry won’t stick
6	Run Boot-Repair	Prefer a graphical tool
7	Enable OS detection, turn off Fast Startup	Windows missing from GRUB
8	Check Secure Boot and UEFI mode	Security errors, entry won’t start

Last updated: November 5, 2026 | Applies to Windows 11 dual-booted with Ubuntu on UEFI PCs