Description of problem:
I have some packages that prevent from upgrading the system, so I used the option --allowerasing but system-upgrade doesn't recognize it.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. sudo dnf system-upgrade download ‐‐allowerasing --releasever=28
dnf system-upgrade: error: unrecognized arguments: ‐‐allowerasing
Run the command right
The problem was actually that I was copying the --allowerasing command from this page: https://fedoramagazine.org/upgrading-fedora-27-fedora-28/
and it seems that it mess up with the characters.
So the solution is to just type it in the command line.