According to the Arks Layer official site:
Changelog
4.0.6.2 (2-7-2018)
- The updating system has been overhauled with better error handling and fixed logging.
- Unfortunately, this means you'll need to download the new Tweaker manually from the website. You win some, you lose some.

So i did...^^;
But i unninstalled the previous version in order to set the new one
However as stated in:

[Tweaker] - Tweaker is failing to open.
By FireFox276
http://www.pso-world.com/forums/show...ailing-to-open

The new update doesn't work and it is recommended to be ignored....

To play i would need the previous version of the tweaker but in the arks site i haven't found any backups
Does anyone know a link to download the previous version (4.0.5.9) of the PSO2 tweaker?