Hi there! Thank you for your report, we're unable to reproduce it however we can offer a few fixes for this solution!
Firstly, CK3 sometimes has a habit of leaving files after uninstalling, to check that, uninstall the game, and go to steam folder for CK3 and make sure it's empty! Then try to reinstall the game and see if it works.
It's a good hygiene step, but this one might work better, it seems like the game is crashing because of it's trying to open the zipped archive for a cloud save.
For this I would suggest to roll back the game version - make a local backup of their cloud saves and remove them from the cloud storage - then go back to live version and try to boot the game again.
Cloud saves can be found here C:\Users\[user_id]\Documents\Paradox Interactive\Crusader Kings III\pops_filestorage\save games.
Let me know how it works out for you.
Cheers!
Firstly, CK3 sometimes has a habit of leaving files after uninstalling, to check that, uninstall the game, and go to steam folder for CK3 and make sure it's empty! Then try to reinstall the game and see if it works.
It's a good hygiene step, but this one might work better, it seems like the game is crashing because of it's trying to open the zipped archive for a cloud save.
For this I would suggest to roll back the game version - make a local backup of their cloud saves and remove them from the cloud storage - then go back to live version and try to boot the game again.
Cloud saves can be found here C:\Users\[user_id]\Documents\Paradox Interactive\Crusader Kings III\pops_filestorage\save games.
Let me know how it works out for you.
Cheers!