Possible fix for vaults not opening

After downloading the latest version of Cryptomator,1.5(appimage73),and converting my only vault I wasn’t able to acess the files inside it.During the unlocking process a screen with java exception error appeared,however I discovered that if I move files and folders with .bkup extension inside the vault to another location
I was able to acess the vaults content.

What did the Java exception error say?