Error when trying to preview

Dear support team,

I have a couple of questions.
First, when I try to preview, an error message occurs. Then, I tried to validate the XLS file, and the following appeared.

If possible can you show me one example of how I can fix the issue? Most of the issues occurred in the matrix questions. How can I solve this problem?

Second, after I finish editing the XLS file, how can I integrate the updated XLS into my initial KOBO questionnaire so that I can view the preview? When I try to run the XLS again by creating a new sheet on the Kobo tool, the format of some sections changes.

Thanks for your help!


Welcome to the community, @Ecolinks! The online validator is fine. Maybe press Preview in browser to see if there are any other issues?

Thanks, @Kal_Lam the online validator is fine. My issue is I don’t understand how I can solve the error it shows. I attached the image to the question. Can you show me how I can fix the error that appears?

These are only warnings: You use groups without a label (begin_group element). This might be intentional, if you do not want to show a group label and the grouping to the user.

See similar previous discussions in the forum (can be found with the search function, please), e.g. Error Loading Form - Failed to Fetch - #5 by wroos. And the ODK documentation Form Logic - ODK Docs.
(@Kal_Lam, might be helpful to add such a hint also to the Kobo Help Center article?)