after install nvidia-340, unable to login with white screen with logout button only

[the Dee]

I just installed and updated Ubuntu 20.10.

During installation of Nvidia proprietry driver, the following error message was appeared
(Everythings were fine with Ubuntu 20.04)

nvidia-340 (340.108-0ubuntu5) 설정하는 중입니다 ...
dpkg: 오류: version '-' has bad syntax: revision number is empty
dpkg: 오류: version '-' has bad syntax: revision number is empty
update-initramfs: deferring update (trigger activated)
INFO:Enable nvidia-340
DEBUG:Parsing /usr/share/ubuntu-drivers-common/quirks/dell_latitude
DEBUG:Parsing /usr/share/ubuntu-drivers-common/quirks/lenovo_thinkpad
DEBUG:Parsing /usr/share/ubuntu-drivers-common/quirks/put_your_quirks_here
Adding system user `nvidia-persistenced' (UID 122) ...
Adding new group `nvidia-persistenced' (GID 130) ...
Adding new user `nvidia-persistenced' (UID 122) with group `nvidia-persistenced' ...
Not creating home directory `/'.
Loading new nvidia-340-340.108 DKMS files...
Building for 5.8.0-20-generic 5.8.0-21-generic
Building for architecture x86_64
Building initial module for 5.8.0-20-generic
ERROR (dkms apport): kernel package linux-headers-5.8.0-20-generic is not supported
Error! Bad return status for module build on kernel: 5.8.0-20-generic (x86_64)
Consult /var/lib/dkms/nvidia-340/340.108/build/make.log for more information.
dpkg: error processing package nvidia-340 (--configure):
installed nvidia-340 package post-installation script subprocess returned error exit status 10
Processing triggers for mime-support (3.64ubuntu1) ...
Processing triggers for libc-bin (2.32-0ubuntu3) ...
Processing triggers for man-db (2.9.3-2) ...
Processing triggers for desktop-file-utils (0.24-1ubuntu4) ...
Processing triggers for initramfs-tools (0.137ubuntu12) ...
update-initramfs: Generating /boot/initrd.img-5.8.0-21-generic
처리하는데 오류가 발생했습니다:
nvidia-340
E: Sub-process /usr/bin/dpkg returned an error code (1)

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: nvidia-340 (not installed)
ProcVersionSignature: Ubuntu 5.8.0-21.22-generic 5.8.13
Uname: Linux 5.8.0-21-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu49
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Sun Oct 11 16:31:40 2020
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=ko_KR.UTF-8
 SHELL=/bin/bash
SourcePackage: nvidia-graphics-drivers-340
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Ani Culequin (culeqino)]

Sorry, but I don't understand anything of that.

I'm just a computer user not a nerd.