CakePHP 4.6 is an API compatible upgrade from 4.0. This page outlines the deprecations and features added in 4.6.
You can can use composer to upgrade to CakePHP 4.6.0:
php composer.phar require --update-with-dependencies "cakephp/cakephp:^4.6"
Note
CakePHP 4.6 requires PHP 7.4 or greater.
RedisEngine now supports a tls option that enables connecting to redis
over a TLS connection. You can use the ssl_ca, ssl_cert and
ssl_key options to define the TLS context for redis.
Optional Command arguments can now have a default value.
Number::formatter() and currency() now accept a roundingMode
option to override how rounding is done.
NumberHelper::format() now accepts a roundingMode option to override how
rounding is done.