CodeIgniter ERR_EMPTY_RESPONSE

My website was running ok when I made an update to a stable version of code and database. These updates are a regular thing, and we do it once in a week to fix small bugs and so on.

The point is that after I ran the migrations, the site started to show ERR_EMPTY_RESPONSE error. Sad thing is that this version of the code is running ok in all development enviroments, same to other production enviroment. Phpinfo() works fine, and IF I change the enviroment to something wrong (i.e. productyonn), CodeIgniter shows me the enviroment is set wrong.

I tried to reverse the commits to version before the update, but the error persists. Did the same to the database.

Here is my .htaccess file, on application/cache

<IfModule authz_core_module>
    Require all denied
</IfModule>
<IfModule !authz_core_module>
    Deny from all
</IfModule>

It is hard to say more things, because I honestly have no ideia about what is going on the server. SysAdmin is not open to an Apache restart, too many systems running on the same apache, he said.