How to fix update-initramfs: failed for /boot/initrd.img-X.X.X with 1 in APT

First, verify that the /boot partition actually has space issues:

df -h /boot

If /boot shows 100% or very high usage (>90%), this is your problem. The initramfs generator needs temporary space to create the new image before moving it into place.

Use apt's automatic removal tool to safely remove obsolete kernel packages:

sudo apt autoremove --purge

This command removes old kernel images and headers that are no longer needed, typically freeing 100-500MB. Verify the cleanup worked:

df -h /boot

If you need more aggressive cleanup, manually list and remove specific old kernels:

dpkg --list | grep linux-image
sudo apt remove linux-image-5.4.0-42-generic  # Replace with actual old version

Important: Never remove the kernel version you're currently running. Check your current version with uname -r.

If autoremove didn't free enough space, you can manually delete old initrd.img files:

ls -la /boot/initrd*
sudo rm /boot/initrd.img-5.4.0-42-generic  # Only remove OLD versions

Each initrd.img file is typically 30-50MB. Make sure you keep the one for your current kernel (check with uname -r).

Once you have freed space, try updating the initramfs again:

sudo update-initramfs -u

For a specific kernel version:

sudo update-initramfs -u -k 5.15.0-56-generic

For all kernels:

sudo update-initramfs -u -k all

Watch for the success message confirming the initramfs was created.

If the error persists after freeing space, there may be broken package dependencies:

sudo apt install -f
sudo dpkg --configure -a

These commands fix broken package installations and reconfigure packages that may have been interrupted. Then retry the update-initramfs command.

As a last resort, force a complete recreation of the initramfs for your current kernel:

sudo update-initramfs -c -k $(uname -r)

The -c flag creates a new initramfs from scratch rather than updating an existing one. This bypasses some corruption issues.