For the latest upgrade, fedup seems to have fallen out of style in favor of new dnf (dandified yum) functionality:

dnf install dnf-plugin-system-upgrade

And the upgrade, first attempt:

dnf system-upgrade download --releasever=23
Fedora 23 - i386                                2.0 MB/s |  39 MB     00:19    
RPM Fusion for Fedora 23 - Free                 1.0 MB/s | 408 kB     00:00    
Fedora 23 - i386 - Updates                      1.8 MB/s |  16 MB     00:08    
RPM Fusion for Fedora 23 - Nonfree              482 kB/s | 129 kB     00:00    
Last metadata expiration check performed 0:00:00 ago on Fri Jan 22 20:10:31 2016.
Error: package perl-Mail-GnuPG-0.21-3.fc22.noarch requires perl(:MODULE_COMPAT_5.20.2), but none of the providers can be installed
(try to add '--allowerasing' to command line to replace conflicting packages)

Take two:

dnf system-upgrade download --releasever=23 --allowerasing
...
Removing:
 kernel                                    i686   4.1.6-201.fc22                         @updates   0  
 kernel-core                               i686   4.1.6-201.fc22                         @updates  40 M
 kernel-devel                              i686   4.1.6-201.fc22                         @updates  35 M
 kernel-modules                            i686   4.1.6-201.fc22                         @updates  16 M
 perl-Mail-GnuPG                           noarch 0.21-3.fc22                            @System   39 k

Total download size: 4.1 G
Is this ok [y/N]:

A few other minor wrinkles, and Fedora 23.