I follow this bug, but same problem:
https://bugzilla.redhat.com/show_bug.cgi?id=1688462
[root@desk mythcat]# dnf system-upgrade download --refresh --releasever=31
--setopt=module_platform_id=platform:f31 --skip-broken
Before you continue ensure that your system is fully upgraded by running "dnf
--refresh upgrade". Do you want to continue [y/N]: y
Fedora Modular 31 - x86_64
17 kB/s | 19 kB 00:01
Fedora - Rawhide - Developmental packages for the next Fedora release
19 kB/s | 19 kB 00:01
Fedora Modular 31 - x86_64 - Updates
28 kB/s | 23 kB 00:00
google-chrome
9.2 kB/s | 1.3 kB 00:00
RPM Fusion for Fedora 31 - Free - Updates
72 kB/s | 76 kB 00:01
Failed to download metadata for repo 'rpmfusion-free-updates'
RPM Fusion for Fedora 31 - Free
27 kB/s | 12 kB 00:00
RPM Fusion for Fedora 31 - Nonfree - Updates
123 kB/s | 76 kB 00:00
Failed to download metadata for repo 'rpmfusion-nonfree-updates'
RPM Fusion for Fedora 31 - Nonfree
15 kB/s | 12 kB 00:00
Fedora 31 - x86_64 - VirtualBox
2.4 kB/s | 6.9 kB 00:02
Failed to download metadata for repo 'virtualbox'
Ignoring repositories: rpmfusion-free-updates, rpmfusion-nonfree-updates, virtualbox
Error:
Problem 1: problem with installed package rpmfusion-nonfree-release-30-1.noarch
- rpmfusion-nonfree-release-30-1.noarch does not belong to a distupgrade repository
- nothing provides system-release(31) needed by rpmfusion-nonfree-release-31-0.3.noarch
Problem 2: problem with installed package rpmfusion-free-release-30-1.noarch
- rpmfusion-free-release-30-1.noarch does not belong to a distupgrade repository
- nothing provides system-release(31) needed by rpmfusion-free-release-31-0.3.noarch
Problem 3: package python2-pwquality-1.4.0-12.fc30.x86_64 requires libpwquality(x86-64) =
1.4.0-12.fc30, but none of the providers can be installed
- libpwquality-1.4.0-12.fc30.x86_64 does not belong to a distupgrade repository
- problem with installed package python2-pwquality-1.4.0-12.fc30.x86_64
Problem 4: package system-config-users-1.3.8-6.fc29.noarch requires python2-libselinux,
but none of the providers can be installed
- python2-libselinux-2.9-1.fc30.x86_64 does not belong to a distupgrade repository
- problem with installed package system-config-users-1.3.8-6.fc29.noarch
Problem 5: package qt5-qtwebengine-freeworld-5.12.4-2.fc31.x86_64 requires
libre2.so.0()(64bit), but none of the providers can be installed
- problem with installed package qt5-qtwebengine-freeworld-5.12.4-2.fc30.x86_64
- re2-1:20160401-11.fc30.x86_64 does not belong to a distupgrade repository
- qt5-qtwebengine-freeworld-5.12.4-2.fc30.x86_64 does not belong to a distupgrade
repository