kernel

Compilation

Upgrade

After installing new kernel dependent ("external") modules needs to be rebuild.
In Debian family dkms is responsible for detecting dependent modules and rebuilding them.
To find which modules needs to be rebuild after upgrade, use: dkms status

Troubleshooting

dkms may yield:

Error! Could not locate dkms.conf file.
File: does not exist.

It means that your installation contains old kernel modules, not properly removed/upgraded.
Kernel modules are usually located in /var/lib/dkms/ (or in /usr/src).
List them: for i in /var/lib/dkms/*/[^k]*/source; do [ -e "$i" ] || echo "$i";done
Remove those that are no longer installed (old ones): rm -rf /var/lib/dkms/something/old_version

References

1. https://forums.virtualbox.org/viewtopic.php?f=7&t=76493#
2. https://wiki.debian.org/KernelDKMS