Hi,
upgrading a VM with SLES11 SP3 to SLES12 on Citrix Xenserver 6.5 SP1 with booting from ISO ends up with a not booting VM. I think the problem is that during the upgrade SLES seems not to see that the system is a VM with Disk /dev/xvda etc. and shows them as /dev/hda etc. Then it tries to install the bootloader in /dev/hda which works without errors, but then the VM doesn't start anymore. Any hints? The second described method in Deployment Guide (7.4.2 Page 116) didn't also not work for me.