Error message

• Warning: date_timezone_set() expects parameter 1 to be DateTime, bool given in format_date() (Zeile 2133 von includes/common.inc).
• Warning: date_format() expects parameter 1 to be DateTimeInterface, bool given in format_date() (Zeile 2143 von includes/common.inc).
• Warning: date_timezone_set() expects parameter 1 to be DateTime, bool given in format_date() (Zeile 2133 von includes/common.inc).
• Warning: date_format() expects parameter 1 to be DateTimeInterface, bool given in format_date() (Zeile 2143 von includes/common.inc).
• Warning: date_timezone_set() expects parameter 1 to be DateTime, bool given in format_date() (Zeile 2133 von includes/common.inc).
• Warning: date_format() expects parameter 1 to be DateTimeInterface, bool given in format_date() (Zeile 2143 von includes/common.inc).
• Warning: date_timezone_set() expects parameter 1 to be DateTime, bool given in format_date() (Zeile 2133 von includes/common.inc).
• Warning: date_format() expects parameter 1 to be DateTimeInterface, bool given in format_date() (Zeile 2143 von includes/common.inc).
• Warning: date_timezone_set() expects parameter 1 to be DateTime, bool given in format_date() (Zeile 2133 von includes/common.inc).
• Warning: date_format() expects parameter 1 to be DateTimeInterface, bool given in format_date() (Zeile 2143 von includes/common.inc).