I had played hardly for about 48 hours until I run from another terminal (Tilix) the
following command, as root, of course: 'dnf upgrade repository-packages
--releasever=27' - just this. The difference between GNOME Terminal 3.24.3 and Tilix
is that Tilix doesn't stop on every install/upgrade/erasing package error, compared to
Gnome Terminal, which is stops the entire command operation, when errors on the way
occurred.
I may say, that it is not the command, that I finally have configured did the main system
upgrade, but the use of Terminal, that don't stop on errors, like the Gnome Terminal.
This what I know, that had made the most of my system. Now I'll reboot and see what
else should I do.