E: Write error - ~LZMAFILE (28: No space left on device)

Got this error this morning doing apt upgrade! Not sure what the issue is, there seems to be plenty of space.

 _   _ ____  _   __  __ _  ___     ______  
| \ | |  _ \(_) |  \/  | || \ \   / /___ \
|  \| | |_) | | | |\/| | || |\ \ / /  __) |
| |\  |  __/| | | |  | |__   _\ V /  / __/
|_| \_|_|   |_| |_|  |_|  |_|  \_/  |_____|
                                           
Welcome to Armbian 21.08.5 Focal with Linux 5.10.63-rockchip64

Calculating upgrade... Done
The following packages will be upgraded:
  armbian-bsp-cli-nanopim4v2 armbian-config armbian-firmware linux-libc-dev
4 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 9,657 kB of archives.
After this operation, 126 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://armbian.tnahosting.net/apt focal/focal-utils arm64 armbian-bsp-cli-nanopim4v2 arm64 21.08.5 [419 kB]
Get:3 http://mirror.12z.eu/pub/linux/armbian/apt focal/main arm64 armbian-firmware all 21.08.5 [7,933 kB]
Get:2 http://armbian.tnahosting.net/apt focal/main arm64 armbian-config all 21.08.5 [126 kB]
Get:4 http://mirror.12z.eu/pub/linux/armbian/apt focal/main arm64 linux-libc-dev arm64 21.08.4 [1,179 kB]
Fetched 9,657 kB in 3s (3,863 kB/s)       
(Reading database ... 84278 files and directories currently installed.)
Preparing to unpack .../armbian-bsp-cli-nanopim4v2_21.08.5_arm64.deb ...
Unpacking armbian-bsp-cli-nanopim4v2 (21.08.5) over (21.08.3) ...
Preparing to unpack .../armbian-config_21.08.5_all.deb ...
Unpacking armbian-config (21.08.5) over (21.08.3) ...
Preparing to unpack .../armbian-firmware_21.08.5_all.deb ...
Unpacking armbian-firmware (21.08.5) over (21.08.3) ...
Preparing to unpack .../linux-libc-dev_21.08.4_arm64.deb ...
Unpacking linux-libc-dev:arm64 (21.08.4) over (21.08.2) ...
Setting up linux-libc-dev:arm64 (21.08.4) ...
Setting up armbian-bsp-cli-nanopim4v2 (21.08.5) ...
Setting up armbian-config (21.08.5) ...
Setting up armbian-firmware (21.08.5) ...
Processing triggers for initramfs-tools (0.136ubuntu6.6) ...
update-initramfs: Generating /boot/initrd.img-5.10.63-rockchip64
update-initramfs: Converting to u-boot format
E: Write error - ~LZMAFILE (28: No space left on device)
Reading package lists... Done
Building dependency tree       
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

pi@data:~$ df /tmp -h
Filesystem      Size  Used Avail Use% Mounted on
tmpfs           1.9G  4.0K  1.9G   1% /tmp
pi@data:~$ df / -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/mmcblk2p1   15G  4.1G  9.5G  30% /