Esta es una forma de crear una sola página de error para todos los errores, que es más fácil de actualizar y mantener.
1) Señale todas las páginas de error en una ubicación en su archivo .htaccess
ErrorDocument 400 /error.php
ErrorDocument 401 /error.php
ErrorDocument 403 /error.php
ErrorDocument 404 /error.php
ErrorDocument 500 /error.php
etc.2) PHP para la página error.php en la raíz
$status = $_SERVER['REDIRECT_STATUS'];
$codes = array(
403 => array('403 Forbidden', 'The server has refused to fulfill your request.'),
404 => array('404 Not Found', 'The document/file requested was not found on this server.'),
405 => array('405 Method Not Allowed', 'The method specified in the Request-Line is not allowed for the specified resource.'),
408 => array('408 Request Timeout', 'Your browser failed to send a request in the time allowed by the server.'),
500 => array('500 Internal Server Error', 'The request was unsuccessful due to an unexpected condition encountered by the server.'),
502 => array('502 Bad Gateway', 'The server received an invalid response from the upstream server while trying to fulfill the request.'),
504 => array('504 Gateway Timeout', 'The upstream server failed to send a request in the time allowed by the server.'),
);
$title = $codes[$status][0];
$message = $codes[$status][1];
if ($title == false || strlen($status) != 3) {
$message="Please supply a valid status code.";
}
// Insert headers here
echo '<h1>'.$title.'</h1>
<p>'.$message.'</p>';
// Insert footer here