error message "value cannot be null"

Hi, I wanted to create a project in Studio 2021, and when I try to import the source text (Word document) I got the following error message: waarde kan niet null zijn. Parameternaam: key
(value cannot be null). I already tried turning off my computer and turning it back on, renaming the document, deleting all images from the source document before importing it, but nothing helped. It is quite urgent so I hope someone can help me?