[NCP] nc-update-nextcloud to 25.0.3 fails because of "free space check failed"

I’ve read all of the threads on this topic but couldn’t find anything helpful for my case. I hope you can help me:)

So, I tried to update my Nextcloud instance to 25.0.3 via nc-update-nextcloud through NextcloudPi panel. Unfortunately, the backup of the current instance fails because there’s not enough free space available.

I’m running Nextcloud on a Hardkernel ODROID C2. The Nextcloud instance is on an 8GB eMMC while the data is stored on an attached 2TB HDD with a full data backup on another 2TB HDD. There’s no data on the eMMC, so var/www/nextcloud/data doesn’t exist. However, the swapfile and dbdir are on the eMMC.

nc-update-nextcloud requires 1139MB of free space. Unfortunately df -h shows only 1011MB available.

What can I do to free up enough space on the eMMC to perform the update? Which files can I safely delete?

ncp@nextcloudpi:/$ df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            828M     0  828M   0% /dev
tmpfs           194M  4.8M  189M   3% /run
/dev/mmcblk1p1  7.0G  5.9G 1011M  86% /
tmpfs           967M     0  967M   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           967M     0  967M   0% /tmp
/dev/zram1       49M   27M   19M  60% /var/log
/dev/sda1       1.9T  921G  943G  50% /media/Backup
/dev/sdb1       1.9T  915G  948G  50% /media/myCloudDrive
tmpfs           194M     0  194M   0% /run/user/1000

I’ve already figured it out myself.
The solution was to move the database (2.2GB) to the external HDD. This way there was enough space for the automatic backup and the update could be installed.