Problem uploading templates.. no logs..?
Error while collecting disk stats from :You gave an invalid object reference. The object may have recently been deleted. The class parameter gives the type of reference given, and the handle parameter echoes the bad value given.
Gert, in both files you attached I see above error but it's not related to issue you having with the templates. This is something about collecting disk statistics from your hypervisor host and nothing to do with templates.
I use to run tail -f on CS mgmt log file and reproduce issue in UI, in this way you always collect correct data.