I guess I found the issue together with someone on GitHub: https://github.com/thopiekar/CuraSolidWorksPlugin/issues/48 and the fix: https://github.com/thopiekar/CadIntegrationUtils/commit/5ab985c2b879bf201160e5734c4897bf5e0a29d7 The problem is visible in the screenshot below: Within my plugin, I'm asking Cura (Python to be precise), where the temporary directory is. Well, as you can see the first answer is "None" (as known as "Nothing" on VisualBasic, which ma