mysqli_fetch_array() Error

[PepeF]

Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in C:\xampp\htdocs\comentarios.php on line 12

$comentarios = mysqli_query($conexion, "SELECT Comentario FROM comentarios WHERE Id_Noticias = '$_GET[noticia]'");
while($comentar = mysqli_fetch_array($comentarios)){
echo $comentar['Comentario'];
}