package shim-signed 1.34.3+13-0ubuntu2 failed to install/upgrade: kmodsign: /var/lib/dkms/nvidia/390.48/4.15.0-13-generic/x86_64/module/*.ko.~signed~: No such file or directory

Happened after checking off "Developer Mode " to help you gyts (Ubuntu) as always, and then updated/upgraded. It asked me to reboot, which I dreaded, but it rebooted fine. I ran update/upgrade again - same error.

ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: shim-signed 1.34.3+13-0ubuntu2
ProcVersionSignature: Ubuntu 4.15.0-15.16-generic 4.15.15
Uname: Linux 4.15.0-15-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
.proc.sys.kernel.moksbstate_disabled: Error: [Errno 2] No such file or directory: '/proc/sys/kernel/moksbstate_disabled'
ApportVersion: 2.20.9-0ubuntu6
Architecture: amd64
Date: Sat Apr 21 06:19:56 2018
ErrorMessage: installed shim-signed package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2018-04-20 (0 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Alpha amd64 (20180409)
Python3Details: /usr/bin/python3.6, Python 3.6.5, python3-minimal, 3.6.5-3
PythonDetails: /usr/bin/python2.7, Python 2.7.15rc1, python-minimal, 2.7.15~rc1-1
RelatedPackageVersions:
 dpkg 1.19.0.5ubuntu2
 apt 1.6.1
SecureBoot: 6 0 0 0 0
SourcePackage: shim-signed
Title: package shim-signed 1.34.3+13-0ubuntu2 failed to install/upgrade: installed shim-signed package post-installation script subprocess returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)