But everything looks great.
I tried the submit the others from the previous studies which I am pretty sure that are working quite well, but I keep getting the same message.
Kindly check your XLS form again, particularly your choices sheet there might an issue with something. Or post a snippet of it to allow people to help you out.
I finally identified the issue and I sorted it out.
Actually, I was getting such error because I was using or_other in the type of questions instead of adding an option called other in the choices.
I read some articles about or_other and it seems like doesn't support multi-language functionality. I have changed it and now it's working properly.
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.