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??
Best Answer
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.