If you saved after all those errors, then yes your save file is probably dead. If you only loaded it, then it is probably fine as the game was likely dead before you even selected the file in the list. Your Strive program folder is probably hopelessly corrupt as this point. There are errors before the backup has loaded, which suggests a botched installation followed by activating the mod system to compound the problem.
I recommend extracting a fresh copy of the game (if you downloaded the zip archive), deleting the mod folder, and making sure you have the correct mod folder in place. It's probably fine to keep the rest of the appdata, but people sometime need to delete that as well.
It is recommended that you start a new progress for the new version of the game, so this is probably for the best. But feel free to keep the saves and try to use them, at worst they will cause errors and you will need to restart the program.