Ubuntu 20.04 Cannot build Virtualbox 6.1 kernel modules

[gmarler]

After upgrading a system from Ubuntu 18.04 (where VirtualBox 5.x and 6.x ran just fine) to 20.04, no version of VirtualBox 5.x or 6.1 has been able to build the VirtualBox kernel modules.

Here's the OS release specifics:

Code: Select all

$ cat /etc/os-release
NAME="Ubuntu"
VERSION="20.04 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal

Here's what happens when the attempt is made, and the diagnostic messages are incredibly sparse, compared with issues like this on previous versions of VirtualBox:

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$ sudo /sbin/vboxconfig
vboxdrv.sh: Stopping VirtualBox services.
vboxdrv.sh: Starting VirtualBox services.
vboxdrv.sh: Building VirtualBox kernel modules.
vboxdrv.sh: failed: Look at /var/log/vbox-setup.log to find out what went wrong.

There were problems setting up VirtualBox.  To re-start the set-up process, run
  /sbin/vboxconfig
as root.  If your system is using EFI Secure Boot you may need to sign the
kernel modules (vboxdrv, vboxnetflt, vboxnetadp, vboxpci) before you can load
them. Please see your Linux system's documentation for more information.

[gmarler@T450s:T2:L1:C2967:J0  ]
~ $ cat /var/log/vbox-setup.log
Building the main VirtualBox module.
Building the net filter module.
Building the net adaptor module.
Building the PCI pass-through module.
Error building the module:
make: *** No rule to make target 'install'.  Stop.

That looks more like a problem with vboxconfig and the scripts that it calls, than with the OS, but can't tell for sure.

Any suggestions?