I use Cryptomator with google drive a take periodic backups. Today when running a backup I have encountered multiple files with io-errors reported in windows. Looking at the Cryptomator app I see events that say “Decryption failed”. It seems those files are no longer recoverable, and anything with this issue since my last backup appears lost. I have not touched the files on google drive for some years directly, relying on Cryptomator with google Drive desktop to sync locally. What could have caused this, is this recoverable and how can I prevent this in future? I’m running Windows 11 with Cryptomator 1.16.0 desktop installed.
Any response to this? It is a pretty serious issue if we’re losing files during upgrades or by some other unknown issue.
Welcome to the Cryptomator communtiy, 
An upgrade of Cryptomator to a newer version does not affect encrypted files. So, either the files were already damaged beforehand or were incomplete at access time (e.g. due to a files-on-deman feature).
You can always download your vault to the local disc and check if the “decryption failed event” still appears.
If the files are damaged, only backups can restore them.