Thank you for your replies. The problem is solved.
Expanding disk capacity is not necessary but /dev/sda2 on /storage was too small and the use was %100.
I have expanded the partition with gparted to maximum and it worked. After expanding, i have noticed that it could even not update the add-ons before. I think previous versions of libreelec was adjusting this automatically. Even though i have resolved my problem, this is still an issue for libreelec 11.0 ova virtual image.