In your production environment when you run the app/console cache:warmup command you need to make sure you run it like this: app/console cache:warmup --env=prod --no-debug
Also, remember that the command will warmup the cache as the current user, so all files will be owned by the current user and not the web server user (eg: www-data). That is probably why you get a 500 server error. After you warmup the cache run this: chown -R www-data.www-data app/cache/prod
(be sure to replace www-data
with your web server user.
Make sure your parameters.ini file has any proper configs in place since its common for this file to not be checked in to whatever code repository you might be using. Or (and I've even done this) its possible to simply forget to put parameters from dev into the prod parmeters.ini file.
You'll also need to look in your app/logs/prod.log to see what happens when you attempt to login.