symfony2 all of a sudden broken?

Question

As much as I love Symfony2, this ain't the first time I come back after not developing for a week, and there is a weird error message...

Warning: Class __PHP_Incomplete_Class has no unserializer in /var/www/my_app/vendor/symfony/src/Symfony/Component/Security/Core/Authentication/Token/AbstractToken.php line 153

I certainly didn't touch that file... Tried googling it but only found some answers where people had used cache:clear command, or installed vendors, or moved entities. As I said, I haven't done anything... I changed the directory name where symfony2 is located, but that shouldn't affect it... Anyways I changed it back later and still same issue. Cache cleared (manually, deleted folders cache and logs) and apache2 restarted...

Anyone run into the same problem before?

Answer 1

Solution is to run the cache:clear command

cd symfony/app
php console cache:clear

and not just manually delete the folders app/cache and app/logs

Answer 2

I had this same problem, and clearing the cache was only a temporary fix. The problem was that there were two instance of Symfony that had conflicting sessions. The way I fixed it was to give each instance of Symfony their own session name in the config.yml

framework:
    session:
        name: "NewSessionName"