TWIMC - FYI
I report that this step was unnecessary for me.
Adjust Whonix Version Number
In dom0.
Open file whonix.jinja with root rights. [3]
Change 14 to 15.
Save.
Please report if this step was necessary or unnecessary for you!
Upon opening the file, (following all the proceeding steps), the version number was already set to 15, so I exited without editing.