This is an ongoing adventure, and I'm starting to lose my mind, so please bear with me for a long explanation on what happened, as I'm trying to understand why is happening and how is happening:

• Raspberry PI 3B with an external HDD and the official power supply.

• My current installation comprises Kodi (With a rather large database), Deluge, PiHole, a samba server to access from my Windows and Linux machines and obviously the Owncloud (10.0.10) installation (With the files in a external hard drive).

I don't really know if this is an Owncloud-specific problem, but it has been coming from Owncloud trying to sync a 200MB pdf file (on a several GB sized library which has been synced over and over during the past years with no issue). We are talking about the client going timeout and the pi freezing and needing a hard reboot.

Thanks to a coincidence, I saw a message telling me that there was no space left on the SD card. I ran dfand saw that, as the message said, there was space problems (Usually we are talking about 82%, this was 99%). I had already the same problem, so I ran sudo apt-get clean (although I ran this every time I did a apt-get upgrade/update combo) but the problem persisted.

Further research led me to

sudo du -h / --exclude /home | grep -P "^{[\d.] M|G\s "} > /accessible-path/du-rootfs.txt

which showed me this:

1,2G /var/cache/lighttpd/uploads

1,2G /var/cache/lighttpd

1,2G /var/cache

At first glance, it looked like this solved the issue, but again, trying to sync from PI to Laptop crashed again the pi, and /var/cache was like this:

382M /var/lib

249M /var/cache/lighttpd/uploads

251M /var/cache/lighttpd

52M /var/cache/apt

Which leads me to think that, somehow, Owncloud is trying really hard to send the file to my laptop, but it crashes when trying to.

And here is when I get lost in this. The only "different" thing I've done is uploading big files. And even this is not something new. The Pi works only on my local network, and has been working for several years with few trouble. I haven't updated the Owncloud client in a while, but it looks like this wasn't the issue. Any ideas on why this is happening?

EDIT: The .user.ini file is the default one (max file sizes of 513M), and the file that gets "locked" while trying to sync is 220MB.