The VirtualBox repository for Fedora 29/30 contains in addition to the correct fedora29 builds also builds for fedora31 which don't work on the older releases.
The update through dnf (haven't testet other methods) only shows the nonworking f31 builds as "newer" and installs them.
Index of /virtualbox/rpm/fedora/29/x86_64
Name Last modified Size
Parent Directory
repodata/ 15-Jan-2020 11:12 -
VirtualBox-5.2-5.2.24_128163_fedora29-1.x86_64.rpm 14-Jan-2019 20:44 76M
VirtualBox-5.2-5.2.26_128414_fedora29-1.x86_64.rpm 28-Jan-2019 10:42 76M
VirtualBox-5.2-5.2.28_130011_fedora29-1.x86_64.rpm 12-Apr-2019 20:25 77M
VirtualBox-5.2-5.2.30_130521_fedora29-1.x86_64.rpm 13-May-2019 20:00 77M
VirtualBox-5.2-5.2.32_132073_fedora29-1.x86_64.rpm 12-Jul-2019 15:04 71M
VirtualBox-5.2-5.2.34_133893_fedora29-1.x86_64.rpm 24-Oct-2019 20:18 71M
VirtualBox-5.2-5.2.36_135684_fedora29-1.x86_64.rpm 14-Jan-2020 19:41 64M
VirtualBox-6.0-6.0.0_127566_fedora29-1.x86_64.rpm 18-Dec-2018 16:31 131M
VirtualBox-6.0-6.0.10_132072_fedora29-1.x86_64.rpm 12-Jul-2019 15:00 110M
VirtualBox-6.0-6.0.12_133076_fedora29-1.x86_64.rpm 03-Sep-2019 18:25 111M
VirtualBox-6.0-6.0.14_133895_fedora29-1.x86_64.rpm 16-Oct-2019 19:14 111M
VirtualBox-6.0-6.0.16_135674_fedora29-1.x86_64.rpm 14-Jan-2020 15:28 103M
VirtualBox-6.0-6.0.16_135674_fedora31-1.x86_64.rpm 14-Jan-2020 15:28 110M
VirtualBox-6.0-6.0.2_128162_fedora29-1.x86_64.rpm 14-Jan-2019 20:24 137M
VirtualBox-6.0-6.0.4_128413_fedora29-1.x86_64.rpm 28-Jan-2019 10:36 137M
VirtualBox-6.0-6.0.6_130049_fedora29-1.x86_64.rpm 16-Apr-2019 15:58 116M
VirtualBox-6.0-6.0.8_130520_fedora29-1.x86_64.rpm 13-May-2019 19:48 116M
VirtualBox-6.1-6.1.0_135406_fedora29-1.x86_64.rpm 11-Dec-2019 20:13 94M
VirtualBox-6.1-6.1.0_135406_fedora31-1.x86_64.rpm 11-Dec-2019 20:13 101M
VirtualBox-6.1-6.1.2_135662_fedora29-1.x86_64.rpm 13-Jan-2020 14:12 94M
VirtualBox-6.1-6.1.2_135662_fedora31-1.x86_64.rpm 13-Jan-2020 14:12 101M
download.virtualbox.org