Hello,
yesterday I updated otree from version 5.9.3 to 5.9.6. In a survey I am currently working on, participants answer (amongst others) a short demographic questionnaire. Questions are coded as integer fields and participants have the option to select "Prefer not to answer" which is encoded as -1 in the data.

Since updating to 5.9.6, everytime I pick "Prefer not to answer" otree shows "Number must be at least 0." as an error on screen. I also tested this in the standard survey included in the otree demo apps. I guess that's not working as intended atm?

Oops! I accidentally pushed the wrong branch. I have now pulled back this release.