# Customize the 404 and 401 pages

> Register ROUTE('#404') and ROUTE('#401') handlers to replace the built-in error pages, and trigger them yourself with $.fallback().

Framework: total5
Product: Total.js 5 (total5@0.0.19)
Language: en
Content-SHA256: 379ed76a90c99ff5446f0f9679ef0c1fd1662cde467d0b7e43332f76bcc6db32
Snapshot: c0700e321579725c5cf4f5ace1ad7d2866d1b4f93c24a63c0b41b6b7998e976c
Sources: total5-installed@total5@0.0.19
Review: not-recorded

When Total.js cannot serve a request it shows a built-in error page. A route whose URL is `#` plus the status code replaces it: `ROUTE('#404', fn)` for "not found", `ROUTE('#401', fn)` for "not authorized", and the same for `#400`, `#431` and others. The handler receives `$` like any route, but **you set the status yourself** with `$.response.status`: Total.js does not do it for you when a custom handler exists. Without a custom handler the built-in page is used and AJAX requests (header `x-requested-with`) get a JSON error instead of HTML.

`$.fallback(code)` sends the current request to the handler for `code`, which is how you answer 404 for a record that does not exist or 403 for a forbidden resource from inside your own code.

```js controllers/errors.js
exports.install = function() {
	ROUTE('#404', not_found);
	ROUTE('#401', unauthorized);
	ROUTE('GET /items/{id}/', item);
	ROUTE('+GET /private/', private_page);
};

var items = { '1': 'First item' };

function item($) {
	var name = items[$.params.id];
	if (name)
		$.json({ name: name });
	else
		$.fallback(404);
}

function private_page($) {
	$.plain('secret');
}

function not_found($) {
	$.response.status = 404;
	$.html('<h1>Nothing here</h1><p>' + $.url.encode() + ' does not exist.</p>');
}

function unauthorized($) {
	$.response.status = 401;
	$.json({ error: 'Please sign in first' });
}

AUTH(function($) {
	$.invalid();
});
```