I'm not very familiar with Linux, so if you want logs, please tell me where to find them.
In case it may not be related to the new Xen version but some other update installed at the same time, here is the update history:
Transaction ID : 13
Begin time : Tue Nov 22 19:56:34 2016
Begin rpmdb : 934:24862fb1256d9f648273fa8d88ac172b1a06d3d9
End time : 19:58:15 2016 (101 seconds)
End rpmdb : 939:d785b8e09d66f2d440768eaa6b01d1e77e21ac7c
User : <user>
Return-Code : Success
Command Line : --exclude=qubes-template-fedora-23,qubes-template-fedora-24,qubes-template-whonix-ws,qubes-template-whonix-gw,qubes-template-debian-8, upgrade
Transaction performed with:
Installed dnf-1.1.10-1.fc23.noarch @anaconda/rawhide
Installed rpm-4.13.0-0.rc1.13.fc23.x86_64 @anaconda/rawhide
Packages Altered:
Upgraded glusterfs-3.7.16-1.fc23.x86_64 @qubes-dom0-cached
Upgrade 3.7.17-1.fc23.x86_64 @qubes-dom0-cached
Upgraded glusterfs-api-3.7.16-1.fc23.x86_64 @qubes-dom0-cached
Upgrade 3.7.17-1.fc23.x86_64 @qubes-dom0-cached
Upgraded glusterfs-client-xlators-3.7.16-1.fc23.x86_64 @qubes-dom0-cached
Upgrade 3.7.17-1.fc23.x86_64 @qubes-dom0-cached
Upgraded glusterfs-libs-3.7.16-1.fc23.x86_64 @qubes-dom0-cached
Upgrade 3.7.17-1.fc23.x86_64 @qubes-dom0-cached
Upgraded libraw1394-2.1.0-6.fc23.x86_64 @anaconda/rawhide
Upgrade 2.1.2-1.fc23.x86_64 @qubes-dom0-cached
Upgraded qubes-core-dom0-3.2.11-1.fc23.x86_64 @qubes-dom0-cached
Upgrade 3.2.12-1.fc23.x86_64 @qubes-dom0-cached
Upgraded qubes-core-dom0-doc-3.2.11-1.noarch @qubes-dom0-cached
Upgrade 3.2.12-1.noarch @qubes-dom0-cached
Upgraded qubes-db-3.2.1-1.fc23.x86_64 @anaconda/rawhide
Upgrade 3.2.3-1.fc23.x86_64 @qubes-dom0-cached
Upgraded qubes-db-dom0-3.2.1-1.fc23.x86_64 @anaconda/rawhide
Upgrade 3.2.3-1.fc23.x86_64 @qubes-dom0-cached
Upgraded qubes-db-libs-3.2.1-1.fc23.x86_64 @anaconda/rawhide
Upgrade 3.2.3-1.fc23.x86_64 @qubes-dom0-cached
Upgraded xfce4-datetime-plugin-0.6.2-6.fc23.x86_64 @anaconda/rawhide
Upgrade 0.7.0-1.fc23.x86_64 @qubes-dom0-cached
Upgraded xfce4-diskperf-plugin-2.5.5-2.fc23.x86_64 @anaconda/rawhide
Upgrade 2.6.0-1.fc23.x86_64 @qubes-dom0-cached
Upgraded xfce4-fsguard-plugin-1.0.2-2.fc23.x86_64 @anaconda/rawhide
Upgrade 1.1.0-1.fc23.x86_64 @qubes-dom0-cached
Upgraded xfce4-systemload-plugin-1.1.2-3.fc23.x86_64 @anaconda/rawhide
Upgrade 1.2.0-1.fc23.x86_64 @qubes-dom0-cached
Upgraded quota-1:4.02-5.fc23.x86_64 @anaconda/rawhide
Upgrade 1:4.02-6.fc23.x86_64 @qubes-dom0-cached
Upgraded quota-nls-1:4.02-5.fc23.noarch @anaconda/rawhide
Upgrade 1:4.02-6.fc23.noarch @qubes-dom0-cached
Upgraded libpng-2:1.6.23-1.fc23.x86_64 @anaconda/rawhide
Upgrade 2:1.6.26-1.fc23.x86_64 @qubes-dom0-cached
Upgraded xen-2001:4.6.1-20.fc23.x86_64 @anaconda/rawhide
Upgrade 2001:4.6.3-21.fc23.x86_64 @qubes-dom0-cached
Upgraded xen-hvm-2001:4.6.1-20.fc23.x86_64 @anaconda/rawhide
Upgrade 2001:4.6.3-21.fc23.x86_64 @qubes-dom0-cached
Upgraded xen-hypervisor-2001:4.6.1-20.fc23.x86_64 @anaconda/rawhide
Upgrade 2001:4.6.3-21.fc23.x86_64 @qubes-dom0-cached
Upgraded xen-libs-2001:4.6.1-20.fc23.x86_64 @anaconda/rawhide
Upgrade 2001:4.6.3-21.fc23.x86_64 @qubes-dom0-cached
Upgraded xen-licenses-2001:4.6.1-20.fc23.x86_64 @anaconda/rawhide
Upgrade 2001:4.6.3-21.fc23.x86_64 @qubes-dom0-cached
Upgraded xen-runtime-2001:4.6.1-20.fc23.x86_64 @anaconda/rawhide
Upgrade 2001:4.6.3-21.fc23.x86_64 @qubes-dom0-cached
Scriptlet output:
1 sed: can't read /etc/sysconfig/prelink: No such file or directory
2 Redirecting to /bin/systemctl start xenstored.service
3 Generating grub configuration file ...
4 Found theme: /boot/grub2/themes/system/theme.txt
5 Found linux image: /boot/vmlinuz-4.4.14-11.pvops.qubes.x86_64
6 Found initrd image: /boot/initramfs-4.4.14-11.pvops.qubes.x86_64.img
7 Found linux image: /boot/vmlinuz-4.4.14-11.pvops.qubes.x86_64
8 Found initrd image: /boot/initramfs-4.4.14-11.pvops.qubes.x86_64.img
9 done
If I re-add them, it is again unable to start.