Would hate to lose all that and have to start completely fresh.
Backup save files first. You can then copy them back if for some reason continuing from where you left the old version fails to work. Discord channel FAQ shows save file location by platform.
Shown error makes me suspect you use Itch App? If so, read FAQ page in wiki, there is explanation for why app does not work.
If that is not it, at what point during updating is that error message showing up?