@Tom-Elliott Yes, this might work, but I didn’t want to spend too much time experimenting. If somebody wants to follow up on this, that’s fine, but I won’t.
@abulhol FOG doesn’t check the free disk space before capturing an image. We consider this something the admin needs to take care of. As well we can’t be really sure how much space a new image would actually take.
@abulhol Fixed in working branch, will be in the next release. Let’s see if we are able to get this out in time so people upgrading their servers from 16.04 to 18.04 won’t run into the same issue as you did.