Hapijs Custom 500 Error Page

Looking through Hapi's documentation, and trying to google, I can find how to setup a 404 page, but I cannot find anything about setting up a 500 page.

I tried adding an error handler like follows:

server.on('internalError', function (request, err) {
    console.log("Internal Error:", err);
    request.reply.view('errors/500', {
        error: err
    }).code(500);
});

But my hook never gets called. Is there an easy way to return a custom 500 page with Hapijs?

You need to trap the error response inside an onPreResponse extension function and set a new HTML response there.

The same principle applies to any Boom error, whether it be one set by you in a handler or set by hapi internally (e.g. a 404 Not found or a 401 Unauthorized from failed auth.

Here's an example that you can try yourself:

index.js

const Hapi = require('hapi');
const Path = require('path');

const server = new Hapi.Server();
server.connection({ port: 4000 });

server.route({
    method: 'GET',
    path: '/',
    handler: function (request, reply) {

        reply(new Error('I\'ll be a 500'));
    }
});

server.ext('onPreResponse', (request, reply) => {

    if (request.response.isBoom) {
        const err = request.response;
        const errName = err.output.payload.error;
        const statusCode = err.output.payload.statusCode;

        return reply.view('error', {
            statusCode: statusCode,
            errName: errName
        })
        .code(statusCode);
    }

    reply.continue();
});


server.register(require('vision'), (err) => {

    if (err) {
        throw err;
    }

    server.views({
        engines: {
            hbs: require('handlebars')
        },
        path: Path.join(__dirname, 'templates')
    });

    server.start((err) => {

        if (err) {
            throw err;
        }

        console.log('Server running at:', server.info.uri);
    });
});

templates/error.hbs

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>{{title}}</title>

    <style>
        body {
            text-align: center;
            background: #B0B0B0;
            color: #222;
        }
        .error h1 {
            font-size: 80px;
            margin-bottom: 0;
        }
    </style>
</head>
<body>
    <div class="error">
        <h1>&#x26a0;<br/>{{statusCode}}</h1>
        <h2>{{errName}}</h2>
    </div>
</body>
</html>

Test it out by going to http://localhost:4000/ to see your custom error page:

This approach catches any Boom response, including those generated internally by hapi rather than by us. Therefore will also work with 4xx errors. Try navigating to http://localhost:4000/notapage and you'll get the same pretty page but for a 404: