NS_ERROR_FAILURE (0x80004005)

[dukemaru]

When I try to open VirtualBox Windows 10 VM (in Linux Mint 20.3 host), I get the following error.
Inaccessible
Virtualbox Document is Empty
Location: '/home/rich/VirtualBox VMs/Windows 10 64-bit/Windows 10 64-bit.vbox', line 1 (0), column 1.
/build/virtualbox-JBwBW7/virtualbox-6.1.34-dfsg/src/VBox/Main/src-server/MachineImpl.cpp[754] (nsresult Machine::i_registeredInit()).
NS_ERROR_FAILURE (0x80004005)
MachineWrap
IMachine {85632c68-b5bb-4316-a900-5eb28d3413df}

I've searched and searched the internet, and so far have found no solution that applies.
I've tried using the Linux Mint version of VirtualBox as well as the download directly from Oracle. Same exact error regardless of which version I use.

Any help would be greatly appreciated!
Thank you.

[mpack]

Look in the VM folder for the backup file called "Windows 10 64-bit.vbox-prev". If it's there then rename it to "Windows 10 64-bit.vbox" to replace the damaged file.

[joelb1]

This solution also worked for a Linux Mint VM running on a Linux Mint machine.

It also allowed a clone to work, when I fixed the master. that makes me suspect the clone wasn't properly cloned or fixing the parent wouldn't have fixed the child.

[dukemaru]

Using the PREV version worked! Thank you!

[mpack]

that makes me suspect the clone wasn't properly cloned or fixing the parent wouldn't have fixed the child.

Not sure what you mean there. If you refer to a linked clone then it obviously requires the parent VM to have a working .vbox file, as that is how the clone gets access to the parent VMs media registry. Fixing the parent definitely would fix the child, if it was the parent that was damaged and not the child.

If you want parent and child to be independent (highly recommended) then create full clones, not linked clones. Linked clones give you a single point of failure affecting multiple VMs: hope you have proper backups!