I need to change to php 5.4 and version 2.1 supports someone help me?

I need to change to php 5.4 and version 2.1 supports someone help me?


I happen to have a script to install that is only compatible with php 5.4

But if I change this version 5.4 as the web already and echo stops working.

I can do to switch to version 5.4 and I keep working?

It is understood?