PHP 8.3 from 8.2: #[Override], typed class constants, readonly clone tweaks, json_validate, str_increment/str_decrement, safer range() and proc_get_status(), assert INI deprecation, and migration pitfalls.

PHP 8.4 upgrade notes (from 8.3): Property Hooks, asymmetric visibility, Lazy Objects, #[Deprecated], request_parse_body(), new Dom\* API, new array_* helpers, and the most important BC breaks & deprecations.

PHP 8.5 from 8.4: |> pipe operator, #[NoDiscard] and (void), closures in constant expressions, ext/uri, FILTER_THROW_ON_FAILURE, Opcache in binary, PDO fetch constant changes, and deprecations to plan for.

Master modern PHP execution environments: Compare PHP-FPM, long-lived application servers (Swoole, RoadRunner, FrankenPHP), and ReactPHP/AMPHP async event loops, while avoiding memory leaks.

PHP 8.1 after 8.0: enums, readonly properties, fibers, intersection/never types, first-class callables—plus $GLOBALS rules, MySQLi exceptions, and a deprecation watchlist.

PHP 5.4 upgrade guide: Learn traits, short array syntax, callable type hints, automatic $this in closures, and how to migrate legacy code after the removal of magic quotes and register_globals.

PHP 5.5 upgrade guide: Learn memory-efficient generators (yield), try-catch finally blocks, the native password hashing API, ClassName::class syntax, and how to migrate away from deprecated mysql and preg_replace /e.

PHP 5.6 upgrade guide: Learn variadic parameters, argument unpacking with ..., the exponentiation operator **, use function/const namespace imports, constant expressions, hash_equals, and strict SSL/TLS defaults.