Here you can repack your Ren'Py game to fix the save file and make it running in the new Ren'Py version.
Beginning with Ren'Py 8.0.x or 8.1, a security check was added to the code which is an attempt to defeat bad actors from interjecting malicious code onto someone's computer via Ren'Py save files. If one attempts to load a save file that has not been generated with the token found on the player's machine, a warning as shown above will appear. If you're confident the save file is clean, you have the choice to allow it to be used.
However, if you manipulate one of your own save files and attempt to use it, regardless of choosing 'YES', the file will not work/load. There are ways to get around this problem as the following describes
Location of Ren'Py security keys file: https://savelocation.net/renpy