vBulletin 4.2.3 work with latest version of PHP 5.6.21?

[dbart]

I tried upgrading my PHP to this latest version and my vBulletin crashed. What is the latest version it will work with?

[Mark.B]

My site is 4.2.3 and runs fine on php 5.6.

Do you have any add ons?

You'll need to tell us exactly what is wrong. 'Crashed' is not enough information.

[Paul M]

The short answer to your question is "Yes" (it will).
There are a few minor bugs, mostly fixed in 4.2.4, but it should not fail.

So as Mark says, you need to be specific, as "crashed" is pretty meaningless.