Can't boot into system after installing newer version of intel-microcode

[Kevin Yeh]

[Summary]
Can't boot into system after installing newer version of intel-microcode at the first time reboot.
If force power off then power on again, machine can boot and reboot normally.
original package version is intel-microcode 3.20180425.
newer package version is intel-microcode 3.20200609.

[Reproduce Steps]
1.Install OS from ubuntu-18.04.1-desktop-amd64.iso and Don't select "download updates while installing" option.
2.Run apt update.
2.Run apt install intel-microcode.
5.Run reboot.

[Results]
Expected:Boot into desktop.
Actual:Only see text "boot in insecure mode" then jump to black screen and no response even press ctrl+alt+del.

[Additional Information]
Base image:ubuntu-18.04.1-desktop-amd64
Product Name:Dell XPS 15 9550
BIOS Version:1.2.21
Kernel Version:4.15.0-118-generic
CPU:Intel i7-6700HQ
RAM:16GB
GPU:Intel Corp. - 8086:191b, nVidia - 10de:139b

[Launchpad Janitor (janitor)]

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