Sorry, if you will lose the work made during your last session, but if there's a bug in your project or the program, it has to be fixed first. Please, [url=mailto:[email protected]]send your .sh3d file to me[/url] if you can't open it, I'll try to repair it and fix the bug that could have provoked this error.

I had imported furniture models created in Blender, and one of these had no materials defined, which could be a cause.

It's not a problem to define no material or have no MTL file.

So there appears to be a number of potential bugs:

Yes, there are miserably still some bugs in Sweet Home 3D, and I make my best to fix them with always a higher priority given to bugs that happen during saving operations.

1. Not warning when an automatic save fails leading to wasted edits

And interrupting your current drawing with a dialog? Note sure it's the best strategy, for problems that happen rarely.

2. Not correctly overwriting a furniture item when importing a modified one

Please, describe a way to reproduce this bug, if you're sure it comes from this handling.

3. Not trapping empty string array when saving.

It's been trapped since you got the error at the moment you save the file! I don't think you would prefer Sweet Home 3D doesn't report any issue and let you think no problem happened...