Where does the ClassNotFound error come from in Symfony2 if the class itself is not used anywhere?

Question

symfony

There is a configured Apache with two (actually more, but it doesn't matter) virtual hosts. On each host projects on the Symphony.
They both worked under Vagrant for a while, but now I'm running them locally for the sake of increased speed.
The problem is that when I go to the first one, I get an error:

ClassNotFoundException in classes.php line 1869:
Attempted to load class "LastLoginListener" from namespace "FOS\UserBundle\EventListener".
Did you forget a "use" statement for another namespace?

At the same time, in this project, my FOSUser is not used at all and is not connected, but in the second one it is used.
Tried to disable hosts and delete entries in hosts - it doesn't work. When clearing the cache - the same thing, but in the console.

Answer 1

The issue is resolved: by my own stupidity, I registered the cache folder for both projects in the same place. The second project created its cache later, apparently, that's why the first one could not decide.