How to fix E: Write error - write (28: No space left on device) in APT

First, determine which partition is full:

df -h

This shows you which mountpoint (/, /var, /boot, etc.) is at 100%. Also check inode usage:

df -i

If IUse% is 100% for any partition even though block usage is low, you have inode exhaustion. Note which partition needs space freed.

The apt cache often contains old downloaded .deb files. Clean them:

sudo apt clean

This removes all cached package files. For aggressive cleaning (removes partial packages too):

sudo apt autoclean

Autoclean keeps only packages for currently installed versions, removing older version packages you may never use again.

Autoremove deletes packages that were dependencies for other packages but are no longer needed:

sudo apt autoremove --purge

The --purge flag also removes configuration files. This often frees significant space if you have upgraded your system multiple times.

If df -h shows /boot is full, you have multiple kernel versions installed. List installed kernels:

dpkg -l | grep linux-image

Keep the current kernel and one previous kernel as backup. Remove old ones:

sudo apt remove linux-image-<old-version>

Replace <old-version> with versions shown in the previous command (not the current running one). You can find your current kernel with:

uname -r

Log files in /var/log can grow extremely large. Safely clean them:

sudo du -h /var/log | sort -h | tail -20

This shows the largest log files. Remove old compressed logs:

sudo rm /var/log/*.gz /var/log/*.old /var/log/*.[0-9].gz

For active logs, truncate them (don't delete, just empty):

sudo truncate -s 0 /var/log/syslog
sudo truncate -s 0 /var/log/auth.log

Use du to find the largest directories:

sudo du -h --max-depth=1 / | sort -h

For deeper investigation of the largest culprits:

sudo du -h --max-depth=2 /var | sort -h | tail -10
sudo du -h --max-depth=2 /home | sort -h | tail -10

Common space hogs: /var/cache, /var/log, /home (user files), and /tmp. Once identified, remove unnecessary files manually or with apt clean commands.

After cleanup, verify space is available:

df -h

If /var or the partition containing /var/cache/apt is now below 90%, retry your apt command:

sudo apt update
sudo apt upgrade

If you still get the write error, check which specific partition is still full and target cleanup there.

If df -i shows 100% IUse% but df -h shows free space, you have inode exhaustion. Find directories with excessive small files:

find /var/log -type f | wc -l
find /var/cache -type f | wc -l
find /tmp -type f | wc -l

Remove small cached files:

sudo rm -rf /var/cache/apt/archives/*
sudo rm -rf /tmp/*
sudo find /var/log -type f -delete

Then verify:

df -i

If space is still insufficient after cleanup, you may need to extend your partition. This requires:1. Unused space on your disk (check with fdisk -l), or
2. Another partition you can shrink

Extending a partition is advanced; ensure you have backups first. Tools like GParted (GUI) or fdisk/parted (CLI) can resize partitions. Alternatively, add a new disk and mount it at /var to distribute storage load.