In docassemble version 0.2.23 there has been a significant change to the way that date fields work. Before, setting "datatype: date" resulted in a variable that was simply a text string like "2018-01-01." Now, the variable will be a Python object representing the date https://docassemble.org/docs/objects.html#DADateTime. This means that you do not have to use the as_datetime() https://docassemble.org/docs/functions.html#as_datetime function on variables defined by datatype: date https://docassemble.org/docs/fields.html#date fields. This change is unlikely to "break" existing interviews, since docassemble's date functions https://docassemble.org/docs/functions.html#date%20functions will work the same regardless of whether their input is a text date or a Python object. However, you will see a difference in the default formatting of a date. Before, writing ${ user.birthdate }, or {{ user.birthdate }} in a .docx file, would yield something like "1985-01-03," but now it will yield "January 3, 1985." For more information, see the documentation: * https://docassemble.org/docs/fields.html#date * https://docassemble.org/docs/objects.html#DADateTime