@black, maybe you should be able to solve this issue if you validate your xlsform through this online validator. The online validator should be able to identify the syntax errors present in your xlsform.
As for the current issue, you get the same when you have a mismatch in your group e.g.
begin_group (when you start a group with a begin_group)
end_group (there should always be an end_group to close the group)
To learn more on this, you could follow one of our post discussed previously:
However, if you are not able to solve your issue, please feel free to share your xlsform with the community. The community should be able to help you solve your issue.