Recently, I tried to upgrade my old OpenELEC 3.2.4 system to LibreELEC 8, which ships with Kodi 17. Things did not go well.
In late 2013, I bought an Intel NUC (model DCCP847DYE, which came with a Celeron 847, an early Sandy Bridge processor). Unbeknownst to me, the CPU had a bug regarding its GPU power management. The XBMC folks had coded around it, so I never knew about it.
The bug surfaced in a big way with LibreELEC 8 — while the upgrade went smoothly, after I was done updating the software, the machine started spontaneously rebooting. Sometimes it would reboot immediately after startup, and sometimes it would take a few minutes. But it never stayed up for more than a few minutes.
Peter Frühberger was the Kodi team dev who explained the issue. I tried to work around it with boot options to disable the RC6 power saving, but that didn’t help, unfortunately. The boot option wouldn’t “take”. So I downgraded to OpenELEC 3.2.4, and thankfully, my userdata remained in place (it was under /storage/.xbmc, as opposed to /storage/.kodi used by LibreELEC). So other than some wasted time, there was no real harm done.