Cannot open old virtual OS after upgrade

[Everest]

I upgraded VirtualBox from 5 to 6. Then I cannot open the previous virtual OS. It gave error message:
=====================
RTR3InitEx failed with rc=-1912 (rc=-1912)

The VirtualBox kernel modules do not match this version of VirtualBox. The installation of VirtualBox was apparently not successful. Executing

'/sbin/vboxconfig'

may correct this. Make sure that you are not mixing builds of VirtualBox from different sources.

where: supR3HardenedMainInitRuntime what: 4 VERR_VM_DRIVER_VERSION_MISMATCH (-1912) - The installed support driver doesn't match the version of the user.
=====================
The error still exists even after I run the suggested command.

I have already put lots of things in the simulated OS (which is Win7). How can I get the virtual OS running?

The host OS is Debian 10.

[scottgus1]

Sounds like you have mixed files from multiple versions of something. Try uninstalling Virtualbox's Extension Pack, then Virtualbox itself. Then install Linux headers again, then Virtualbox again, see https://www.virtualbox.org/manual/ch02. ... nux-prereq.