Symfony Cache doctrine/orm/Proxies failed to open stream /Proxy/AbstractProxyFactory.php on line 209

You did not create the proxy classes before you tried to access your application. This is usually done by:

app/console cache:warmup --env=prod

The auto-generation of proxy-classes is disabled by default in the prod environment. You can enable automatic generation of proxy-classes similar to the dev environment by adding this to your config:

app/config/config_prod.yml

doctrine:
    orm:
        auto_generate_proxy_classes:  true # <- change to true
        proxy_dir:            '%kernel.cache_dir%/doctrine/orm/Proxies'
        proxy_namespace:      Proxies