In general it doesn't matter "how much" two images differ. What is relevant are the changes to the graph of objects that are part of a snapshot, and that includes changes to classes that are either part of the graph or have instances that are part of the graph.

It is possible to reshape objects upon loading (https://rmod.inria.fr/web/software/Fuel/Version1.9/Documentation/Migration) but it is certainly not automatic (some automatic migrations are possible).

One particular problem that can pop up, if you fuel out methods, are methods who's bytecode has changed. Fuel will then stop with an error.

On 8/30/17, Tim Mackinnon <tim@testit.works> wrote:
> Actually in my case they are similar but not identical images.

Good to know a slightly different image still can cope with a fuel
file written by another image.

Probably the results depends on which types of objects you have written.

Not sure about the influence of changes in class definitions.

--Hannes

> The Lambda image is a minimal early 7.0 one - but it is beforecthe massive
> reworks that were announced. On top of this it has my project loaded.
>
> The OS X image is a fat 6.1 with the same project loaded. (So a superset).
>
> I am saving the walkback context.
>
> Fuel warns that images need to be similar for it to map objects - so my
> scenario fits that (the same image would be easier I assume).
>
> Tim
>
> Sent from my iPhone