Error message

• Warning: date_timezone_set() expects parameter 1 to be DateTime, boolean given in format_date() (line 2062 of /data/sites/potowski.org/includes/common.inc).
• Warning: date_format() expects parameter 1 to be DateTimeInterface, boolean given in format_date() (line 2072 of /data/sites/potowski.org/includes/common.inc).