Fatal error: Uncaught TypeError: strtotime(): Argument #2 ($baseTimestamp) must be of type ?int, string given in /in/887ZR:2
Stack trace:
#0 /in/887ZR(2): strtotime('-1 month', '2013-10-31')
#1 {main}
thrown in /in/887ZR on line 2
Process exited with code 255.