MySQL query works but PHP returning Exception: errorinfo:null
===

The following code updates the table correctly, but it also returns an Exception. Any idea what might be happening here?

<!-- language: php -->

    public function updateThis($aaa){
	try
	{
		$success = false;
	
		$query = "
			UPDATE this_table
			SET thing = '0'
			WHERE aaa = :aaa";
		
		$stmt = $this->conn->prepare($query);
		
		$stmt->bindParam(':aaa', $aaa);
		
		$stmt->execute();
		
		if($this->conn->commit())
			$success = true;
				
		return $success;
	}
	catch(Exception $e)
	{
		return $e;
	}
    }