Calling this method on a static property that is not public will return a ReflectionException stating the property does not exist. This is quite misleading as the property is valid.class test { public static $publicProperty = 'public'; private static $privateProperty = 'private'; public static function printProperties() { echo self::$publicProperty . "\n"; echo self::$privateProperty . "\n"; }} $reflectedClass = new \ReflectionClass('test');$reflectedClass->setStaticPropertyValue('publicProperty', 'foo');$reflectedClass->setStaticPropertyValue( 'privateProperty', 'bar' );PHP Fatal error: Uncaught exception 'ReflectionException' with message 'Class test does not have a property named privateProperty'If you retrieve the method using the reflection class getProperty method you can circumnavigate this issue$reflectedProperty = $reflectedClass->getProperty('privateProperty');$reflectedProperty->setAccessible(true);$reflectedProperty = $reflectedProperty->setValue('bar');test::printProperties(); will echofoobar