Apache enable worker mpm

After some time of working i did it myself. You can find the steps below.

Check which MPM apache is currently running:

apachectl -V | grep -i mpm

Result:
Server MPM:     prefork

List Available MPM Modules (Make sure mpm_worker is listed)

ls /etc/apache2/mods-available/mpm*

Result:
/etc/apache2/mods-available/mpm_event.conf  /etc/apache2/mods-available/mpm_prefork.conf  /etc/apache2/mods-available/mpm_worker.conf
/etc/apache2/mods-available/mpm_event.load  /etc/apache2/mods-available/mpm_prefork.load  /etc/apache2/mods-available/mpm_worker.load

List Enabled MPM Modules (If mpm_worker is not enabled we should enable it and disable the mpm_prefork module)

ls -l /etc/apache2/mods-enabled/mpm*

Result:
/etc/apache2/mods-enabled/mpm_prefork.conf -> ../mods-available/mpm_prefork.conf
/etc/apache2/mods-enabled/mpm_prefork.load -> ../mods-available/mpm_prefork.load

Disable MPM_PREFORK module

a2dismod mpm_prefork

Enable MPM_WORKER module

a2enmod mpm_worker

To check if Apache is running on MPM WORKER

apachectl -V | grep -i mpm

Result:
Server MPM:     worker

If you get this error after executing these commands:

Apache is running a threaded MPM, but your PHP Module is not compiled to be threadsafe. You need to recompile PHP

Try to remove libapache2 package:

apt-get remove libapache2-mod-php5

Apache is running a threaded MPM, but your PHP Module is not compiled to be threadsafe. You need to recompile PHP.