I'm thinking of updating my php from version 5.3 to version 5.5.

I was wondering if 5.5 is backwards compatible with 5.3 as it is 'just' a minor update (eg not 5.3 to 6.4). Am I running into problems if I just update the php installation via https://serverfault.com/a/420288/124883 ? Is there a way (just like nginx's 'configtest' option to test the dependencies? )

Or is it possible to have both versions running simultaneous as I don't have a test-server only a live server??

2 Answers 2


PHP 5.3 is not 100% backwards compatible with PHP 5.5. An important change is that the old fashioned mysql connector (http://php.net/manual/en/book.mysql.php) is deprecated.

More info on deprecated functions for PHP 5.4 => PHP 5.5: http://php.net/manual/en/migration55.deprecated.php

PHP 5.3 => PHP 5.4: http://php.net/manual/en/migration54.deprecated.php

I highly suggest to do a grep on your source.

  • I'm only using postgresql via the PDO connector, so that shouldn't be a problem.
    – stUrb
    Aug 19, 2014 at 13:59
  • In that case you only have to apply a grep for the rest. Luckily there are not that many deprecated functions left for you to search.
    – Skiaddict
    Aug 19, 2014 at 14:36

PHP 5.4 and 5.5 could display more warnings on different things. Depending on the PHP applications, those warnings / errors can be visible to the end user also.

Therefore I recommend you to upgrade the PHP in your test environment, and test if things work as they should, before you upgrade it in your production environment.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.