Can't boot VMs after host kernel upgrade (CentOS8)

I followed this article to upgrade the kernel of one of our Linux server runs CentOS8. According to that article, upgrade the kernel of a CentOS system is rather simple, you just need to run the following command as root:

rpm --import
dnf -y install
dnf -y --enablerepo=elrepo-kernel install kernel-ml

Everything goes fine before I try to boot up one of the VM in Virtualbox 6.

Boot failure, "The system is currently not set up to build kernel modules, please install the Linux kernel header files matching the current kernel.", it says.

Obviously, we need the correct header file, after digging a while on Google, I didn't get an answer. Then I review the steps I have done to upgrade the kernel. Oh, I got the solution below:

dnf -y --enablerepo=elrepo-kernel install kernel-ml-devel
/sbin/rcvboxdrv setup

Problem resolved.