PHP version upgrade 5.3.25 to 5.6

Question

We have a requirement for upgrading the PHP version (5.3.25) to current stable version which is 5.6.17. So, for this we need to find which approach would be best.

Answer 1

PHP maintainers upload list of incompatible changes of every release. Here are the documents you may want to read:

• 5.4 incompatible changes
• 5.5 incompatible changes
• 5.6 incompatible changes

If you have regression tests, you're the lucky man; if you don't, i strongly recommend test every change in virtual environment before real environment update on main server. If you're brave enough, you can try to setup vagrant - this will allow developers to easily share their environment and to reproduce server state as it should be after upgrade to 5.6.

I also wouldn't recommend partial upgrades, i think it's better to target for 5.6 at the first (and only) migration step.