Hi, You can download the previous releases at https://github.com/chrismaltby/gb-studio/releases, you'll want 2.0.0-beta5. Though you'll need to open your backup version as migrated projects can't be opened in older versions.
Judging by the error you're seeing there it looks like you might have a "Set Actor Sprite Sheet" event that is switching an actor to use a sprite that's been deleted, if you check through all of them you should hopefully find the source of the problem.
I've also just written a fix for the error you're seeing which will be included in a bug fix release GB Studio 3.0.1 hopefully within the next few days.
Thanks for reply and that link :)
I made copy of my project before i open it in gb studio 3 so i can open that original project in gb studio 2 again.
And also many thanks for you made this program with many and many opotions to be creativa and in what i can make super games what i can play on my old gameboy. It alvays make me hapy work on game in your program :)
you did good work and thanks good you continue in it. Many thanks for everything.