"Illegal VDI transition : activated RO -> activated RW ."

The solution howto fix this error "Illegal VDI transition

: activated RO -> activated RW ." for novice users:

Use Xen Server Console or connect by SSH to the xen server:

1) I use SSH and conect to Server:
radek@desktop:~$ ssh [email protected]

2) Then look for the VM with a name beginning with the "Transfer VM for VDI"
root@xen3 ~# xe vm-list

....

uuid ( RO) : d79c5ac0-6c4d-f1b1-6a3e-1bfb08d305a0
name-label ( RW): vm3.avt.xxxxxxxx
power-state ( RO): running

uuid ( RO) : e2654fc3-4a30-c624-bb63-56782e1a4a20
name-label ( RW): vm9.avt.xxxxxx - local old
power-state ( RO): halted

uuid ( RO) : ca9977f3-e6e8-4871-15f7-077e985d20b8
name-label ( RW): Transfer VM for VDI 0247f0bf-e897-47c4-8c77-8df50090b951
power-state ( RO): running

....

3) We stop the found VM (using the uuid):
xe vm-shutdown uuid=ca9977f3-e6e8-4871-15f7-077e985d20b8

Done! And now we can run the VM using XenCenter.