How to Remove Old Kernels on Linux

What Causes This?

Old Linux kernels build up over time as your distribution installs newer versions but keeps previous ones for rollback and compatibility. If you use WSL, dual-boot Linux, or Linux tools inside Windows, these leftover kernel packages, headers, and boot files can take up unnecessary disk space. The problem usually happens when automatic cleanup doesn’t run or older packages are marked to stay installed.

Common Symptoms

• Your Linux partition or WSL virtual disk keeps growing
• You see multiple old kernel versions listed in your package manager
• System updates fail because there isn’t enough free space
• /boot or the Linux system drive is nearly full
• You notice old kernel headers and modules still installed after updates

How to Fix It Manually

1. Check which kernel you’re currently using

   • Open your Linux terminal.
   • Run:

     uname -r

   • Make a note of the version shown. Do not remove the kernel currently in use.

2. List installed kernels

   • On Ubuntu or Debian-based systems, run:

     dpkg --list | grep linux-image

   • You may also want to check related packages:

     dpkg --list | grep linux-headers

   • Look for older versions that don’t match the output from uname -r.

3. Remove old kernels on Ubuntu or Debian

   • For each old kernel version, remove its image and headers. Example:

     sudo apt remove linux-image-5.15.0-60-generic linux-headers-5.15.0-60-generic

   • If you want APT to clean unused kernel packages automatically, run:

     sudo apt autoremove --purge

   • Read the package list carefully before confirming. Make sure the current kernel is not included.

4. Remove old kernels on Fedora, RHEL, or CentOS

   • List installed kernels:

     rpm -q kernel

   • Remove an older one with:

     sudo dnf remove kernel-<version>

   • On some systems, this also works to remove unused packages:

     sudo dnf autoremove

5. Update the bootloader if needed

   • On Ubuntu or Debian, run:

     sudo update-grub

   • On some Fedora-based systems, GRUB updates automatically, but if needed you can rebuild the config using your distro’s GRUB command.

6. Reboot and verify

   • Restart the Linux system.
   • After reboot, check the active kernel again:

     uname -r

   • Confirm the system starts normally and that disk space has improved:

     df -h

7. If you use WSL on Windows, compact the virtual disk afterward

   • Close all WSL instances in Windows Terminal or Command Prompt:

     wsl --shutdown

   • If you’re using WSL2, the Linux cleanup may not immediately shrink the .vhdx file until you compact it separately from Windows.

Fix It Automatically with Kudu

If you’re using Linux tools through WSL or dealing with storage bloat on a Windows PC, Kudu can help find large leftover system files, reclaim wasted space, and simplify cleanup without digging through package lists manually. It’s a faster way to spot what’s safe to remove and keep your PC from filling up again.

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