Same Videodatabase problem here running MariaDB 10.1 (Windows).
Upgraded to 10.2, but then the database serivce didn't start any more.
Had to kick out 'innodb_additional_mem_pool_size=32M' from my.ini first, after that I directly upgraded to 10.3 and RC5 works as expected since then.
So: thanx again to the Kodi-Team for reminding me to upgrade the background services once in a while as well