Disable SELinux
/usr/sbin/setenforce 0
RPM
Upgrading a system with dnf
1 # Install all updates for currently installed version of Fedora
2 sudo dnf upgrade --refresh
3 # Make sure dnf's system upgrade plugin is installed
4 sudo dnf install dnf-plugin-system-upgrade fedora-upgrade
5 # Download packages for the desired version, e.g. Fedora 26
6 sudo dnf system-upgrade download --refresh --releasever=26
7 # Upgrade
8 sudo fedora-upgrade