'Symfony\Component\ClassLoader\ClassCollectionLoader' not found in /xxxx/xxxx/xxxx/app/bootstrap.php.cache

Question

recently I'm updating my Symfony 2 project from "2.3" to "2.8"

I'm getting

'Symfony\Component\ClassLoader\ClassCollectionLoader' not found in /xxxx/xxxx/xxxx/xxxx/bootstrap.php.cache

when my Ckfinder tried to call Symfony\Component\HttpKernel\Kernel->doLoadClassCache()

These are what I have tried :

1. Clearing production cache
2. Building new bootstrap file using composer
3. Updating dependencies using composer

Answer 1

I've recently found out that the config.php of the ckfinder doesn't include app/autoload.php. Thank you.