Upgrading my symfony application from 4.4 to 5.1

July 4th, 2020

Just a short overview of what I did to update my symfony applications to 5.1

Update composer dependencies

First, I updated my composer.json according to the instructions here

  • Changed all 4.4.* lines to 5.1.*

  • Change the extra.symfony.require line in composer.json

        "extra": {
            "symfony": {
                "require": "5.1.*"
  • Run the update.

    composer update "symfony/*" --with-all-dependencies

Remove symfony/web-server-bundle

During the update, I ran into a version error with the symfony/web-server-bundle package.

Doing some research, It looks like we can now use symfony's cli tool to start local servers, so I simply removed this package and re-ran the update command.

composer remove symfony/web-server-bundle
composer update "symfony/*" --with-all-dependencies

Replace twig.yml with framework.yml

Reloading the application, I started getting errors with my config/routes/dev/twig.yaml file, specifically about the line @TwigBundle/Resources/config/routing/errors.xml

To fix this

  • Replace the file name to framework.yml
  • Replace _errors.resource with the updated class
    # config/routes/dev/framework.yaml
        resource: '@FrameworkBundle/Resources/config/routing/errors.xml'
        prefix: /_error

Update reference to new Debug class

I then ran into the error Fatal error: Uncaught Error: Class 'Symfony\Component\Debug\Debug' not found in public/index.php:12 Stack trace: #0 {main} thrown in public/index.php on line 12

To fix this

  • Update the Debug class
    // public/index.php
    // This used to be "use Symfony\Component\Debug\Debug;"
    use Symfony\Component\ErrorHandler\Debug;

Replace depreciations

This is not required but It is best to move away from depreciated code.

  • Update my configureRoutes() method in Kernel.php to use the new RoutingConfigurator class.

    // old src/Kernel.php
    use Symfony\Component\Routing\RouteCollectionBuilder;
    protected function configureRoutes(RouteCollectionBuilder $routes): void
        $confDir = $this->getProjectDir().'/config';
        $routes->import($confDir.'/{routes}/'.$this->environment.'/**/*'.self::CONFIG_EXTS, '/', 'glob');
        $routes->import($confDir.'/{routes}/*'.self::CONFIG_EXTS, '/', 'glob');
        $routes->import($confDir.'/{routes}'.self::CONFIG_EXTS, '/', 'glob');
    // new src/Kernel.php
    use Symfony\Component\Routing\Loader\Configurator\RoutingConfigurator;
    protected function configureRoutes(RoutingConfigurator $routes): void
        if (file_exists(\dirname(__DIR__).'/config/routes.yaml')) {
        else {
            $path = \dirname(__DIR__).'/config/routes.php';
            (require $path)($routes->withPath($path), $this);

— and Voila!

My application was updated to the latest stable version without any depreciations!