I have a troubleshooting step to share that can resolve the error, Benjamin.

Are you getting an error message that says "Your file is too big to export" when converting your file? The file can only have a maximum of 350,000 targets in order to import.

You might want to condense your data before converting the file. Follow the steps from this article on how to do that: Use the Condense Data utility.

You can also check out this article if you're getting a different error: How to fix errors when converting from QuickBooks Desktop to QuickBooks Online.

Please add a reply below if you have follow-up questions. I'll get back here to answer them as soon as I can.