N: Skipping acquire of configured file ‘contrib/binary-i386/Packages’ as repository ‘https://download.virtualbox.org/virtualbox/debian bionic InRelease’ doesn’t support architecture ‘i386’

N: Skipping acquire of configured file ‘contrib/binary-i386/Packages’ as repository ‘https://download.virtualbox.org/virtualbox/debian bionic InRelease’ doesn’t support architecture ‘i386’

There’s no 32bit support now so update the source list file to get rid of the warning.

In my case, /etc/apt/sources.list.d/virtualbox.list

Change

deb https://download.virtualbox.org/virtualbox/debian bionic contrib

to

deb [arch=amd64] https://download.virtualbox.org/virtualbox/debian bionic contrib