Some of you may have seen recently that there was a new feature announced called "formInputs". In oTree 5.9 this has been tweaked slightly and renamed to 'forminputs' (with a lower-case i). If you used 'formInputs', make sure to update your code accordingly.

https://otree.readthedocs.io/en/latest/forms.html#javascript-access-to-form-inputs