Interface 'Symfony\Component\HttpKernel\HttpKernelInterface' not found

Question

After upgrading from Symfony 2.3 to 2.8 I get the following error:

Fatal error: Interface 'Symfony\\Component\\HttpKernel\\HttpKernelInterface' not found in app/bootstrap.php.cache on line 2629

Already tried removing the vendor folder and doing a composer install.

Any ideas?

Answer 1

Have you tried removing cached code? It seems like you've procompiled your application into one file bootstrap.php.cache . Have you tried removing it.

Otherwise it is always a good idea to do two of the following commands:

php composer.phar dump-autoload - update autolod file
php app/console cache:clear - removes cache

Answer 2

I had to add the following line to web/app.php and web/app_dev.php:

$loader = require __DIR__.'/../app/autoload.php';

And also update app/console.

Found this by comparing my files with a fresh install of Symfony 2.8