I can't submit the xlsx form into https://getodk.org/xlsform/

Welcome to both of you! Please take a moment to introduce yourself when you have a moment, it's always great to hear more about how everyone is using ODK.

Thanks so much for coming back to share what you figured out, @Arlindo_Malheia. The error message is clearly very bad so I've filed an issue to try to improve things there.