In yesterday's video forum, @Kari correctly said you need to put the Viboot VM depository on a different drive.
Suppose you have a 200 GB drive, and it is only using 50GB.
When you use viboot, it requires 200GB spare space even if the partitions only require 50GB, so as you only have 150GB spare, it will not fit. You can use a different drive with 200GB spare
So what do you do if you only have one drive (or less spare space on a other drive)?
You can use external drives but that is not always convenient and can be slow.
Here are some screen dumps showing how to use viboot if you only have one drive
Picture 1 shows my disk. I shrank the C drive as below fist and then backed up drive
Picture 2 shows backup image. Note "reserved space" of 166.74 GB. This is what causes problem in using viboot on same drive as viboot thinks it needs that space as well as partitions, and then there is not enough space on hard drive.
Picture 3 shows solution.
Basically you restore above image to a virtual hard drive sized for the actual partitions, using drag and drop. You have to use type expandable for the VHD as it only uses a few MB when empty.
Now you image backup the virtual hard drive, and Viboot only needs 60 GB space. and will work on same drive.
Note - if you save and create new image, when you restore it, you need to re-expand C drive (and move partition 6). You could of course have dragged partition 6 to left of 4 and then images so 4 is on the right.
Note: this method will not work if the existing drive is more than 50% full (40% realistically). to allow for saving a new image. You have to use a second drive in this case. You can still use above to decrease space needed on another drive.
A good change to Macrium Reflect would be an option to ignore unallocated spaces when creating the image backup i.e. do what I did above in effect during the initial imaging automatically, in effect the disk size would be just be the sum of all allocated partitions.