Some times if you have php version conflicts it happens To overcome that please follow the below steps
Step 1 : Yum list installed | grep 'php'
if you have multiple versions of php like php 5.6 and php 7.0 this confilict will happens
Step 2 : yum remove **your php version **
Step 3 : Then restart the apapche /etc/init.d/httpd restart
or service apache2 restart