hamedkouhfallah install the latest version, without any other extensions except the bundled ones. Do a complete install the replace the database with your beta 12 database, run php flarum migrate. If all goes well copy over assets to public/assets and slowly install extensions you need (don't blindly copy them over as many have been superceded or abandoned) based on the availability on extiverse.
Do not do this live, make a backup of files and database!
There's also the extiverse upgrade helper https://discuss.flarum.org/d/25246-extiverse-helper
