make[1]: *** No rule to make target 'modules'. Stop.

[OPSTime]

OS: PVE 6.1-7
$ uname -a
Linux dragon 5.3.18-2-pve #1 SMP PVE 5.3.18-2 (Sat, 15 Feb 2020 15:11:52 +0100) x86_64 GNU/Linux

$ cat /etc/debian_version
10.3

$ DRV_NAME=rtl8812AU
$ DRV_VERSION=5.6.4
$ mkdir /usr/src/${DRV_NAME}-${DRV_VERSION}

$ wget http://download.proxmox.wiki/debian/pve/dists/buster/pve-no-subscription/binary-amd64/pve-headers-5.3.18-2-pve_5.3.18-2_amd64.deb

$ dpkg -i pve-headers-5.3.18-2-pve_5.3.18-2_amd64.deb

$ dkms build -m ${DRV_NAME} -v ${DRV_VERSION} --kernelsourcedir /usr/src/linux-headers-5.3.18-2-pve

Preparing kernel 5.3.18-2-pve for module build:
(This is not compiling a kernel, just preparing kernel symbols)
Storing current .config to be restored when complete
Running Generic preparation routine
make mrproper...(bad exit status: 2)
Warning: using /usr/src/linux-headers-5.3.18-2-pve/.config
(I hope this is the correct config for this kernel)
make oldconfig...(bad exit status: 2)
make prepare-all...(bad exit status: 2)

Building module:
cleaning build area...
'make' KVER=5.3.18-2-pve...(bad exit status: 2)
Error! Bad return status for module build on kernel: 5.3.18-2-pve (x86_64)
Consult /var/lib/dkms/rtl8812AU/5.6.4/build/make.log for more information.
root@dragon:/usr/src/rtl8812AU-5.6.4# less /var/lib/dkms/rtl8812AU/5.6.4/build/make.log
root@dragon:/usr/src/rtl8812AU-5.6.4# cat /var/lib/dkms/rtl8812AU/5.6.4/build/make.log
DKMS make.log for rtl8812AU-5.6.4 for kernel 5.3.18-2-pve (x86_64)
Tue 02 Jun 2020 10:30:47 PM CST
make ARCH=x86_64 CROSS_COMPILE= -C /lib/modules/5.3.18-2-pve/build M=/var/lib/dkms/rtl8812AU/5.6.4/build modules
make[1]: Entering directory '/usr/lib/modules/5.3.18-2-pve/build'
make[1]: *** No rule to make target 'modules'. Stop.
make[1]: Leaving directory '/usr/lib/modules/5.3.18-2-pve/build'
make: *** [Makefile:2289: modules] Error 2

$ cat /var/lib/dkms/rtl8812AU/5.6.4/build/make.log

DKMS make.log for rtl8812AU-5.6.4 for kernel 5.3.18-2-pve (x86_64)
Tue 02 Jun 2020 10:30:47 PM CST
make ARCH=x86_64 CROSS_COMPILE= -C /lib/modules/5.3.18-2-pve/build M=/var/lib/dkms/rtl8812AU/5.6.4/build modules
make[1]: Entering directory '/usr/lib/modules/5.3.18-2-pve/build'
make[1]: *** No rule to make target 'modules'. Stop.
make[1]: Leaving directory '/usr/lib/modules/5.3.18-2-pve/build'
make: *** [Makefile:2289: modules] Error 2