This article is aimed at English learning and memorandums.
Since the author is Japanese and supports Japanese, error handling may differ between different overseas versions.
Please note. m (_ _) m

Background

I tried to install VirtualBox → CentOS8 to touch Linux on Mac, but there was a problem that it returned to the initial screen as if nothing happened even if I installed it many times.
I was stuck for about a day and a half, saying, "Compatibility of Catalina just released? Or setting of security software? Or something damaged during download, or ...".

Development Environment

・ VirtualBox: 6.0.14 r133895
・ Host OS: MacOS Catalina 10.15
・ Guest OS: CentOS 8.0.1905

Cause & Solution

The cause was that the HDD priority of the boot media at the time of startup was lower than the optical. (* The image has been modified.)
It seems that the initial screen was displayed (but the capacity was buried by installation) if the HDD was later to select CentOS installed by the boot loader by restarting.

Other

Please point out any mistakes in expression, etc., because they are poor English engineers and they are learning.🙇‍♂️
Thank you for reading!

ありがとうございました！