Matrix question error: nGroup has no children! Missing label?

I have two matrix questions in my survey that are producing validation errors when I try to deploy.

Message from Kobo: Unexpected KoBoCAT error 400: b’{“detail”:“ODK Validate Errors:\nGroup has no children! Group: ${group_vc58y34}. The XML is invalid.\n\n>> Xform is invalid! See above for errors and warnings.\n\nThe following files failed validation:\n${tmpk2k7gvyn}\n\nResult: Invalid”}’

I downloaded the XLS and ran in through the validation program (ODK - XLSForm Online v2.x) and found that all the rows in my matrixes have the same issue. Example below:

[row : 41] Group has no label: {‘name’: ‘IHS_trainings_header’, ‘type’: ‘begin_group’}

In XLS, I see the Label is missing (see screenshot), but I do not see how to fix this in the Kobo form.

Please advise. Thank you!

Welcome to the community, @nau_cher_chr! It would always be easy to start building a matrix question through the form builder and giving a finishing touch through the XLSForm. Doing this should minimize the chances of having issues while building a form with matrix question.

Thanks, @Kal_Lam,
Might be great to add this hint to the KoBo documentation?
Kind regards

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I did build the question in the Kobo form builder online. (See screenshot of question below) I only downloaded the XLS to see if I could find the error after I got the error message when I tried to deploy.

@nau_cher_chr, do you get the same error message again?

Yes. I tried deleting the question entirely from the form and re-building it - but I still got the same error.

Maybe you missed changing the form layout to grid?

I saw that using a matrix requires that the form layout be “grid,” so I made sure to select that option. But I noticed that when I leave the form and sign back in, the form ‘forgets’ my selection and defaults back to single page. So, every time I edit the form, I have to re-select the “grid” option.

Maybe you will also need to SAVE the changes you made? Kindly please feel free to reach us back even if saving does not solve your issue?