%s::__sleep() should return an array only containing the names of instance-variables to serialize

Description

The return type of __sleep is actually array, even when it is not mentioned. Any other returned value generate this error.

Example

<?php

class X {
    function __sleep() {
        return 1;
    }
}

serialize(new X);

?>

Solutions

  • Return an array from __sleep.

  • Add the return type array and return an array from __sleep.

  • Remove the __sleep() method.