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Looks like a virtual hard drive failure.
Either trash the VM and re-import it. OR
Try fix the virtual hard drive file system issue. Make a backup before you start in case any important data there. We don’t have documentation how to fix file system corruption yet.
You could try to fix it as per Free Support for Whonix ™ since there is nothing Whonix specific about that issue or maybe someone else can assist with that.