PHP 7.4 now available on Heroku
Change effective on 10 February 2020
PHP 7.4 (release 7.4.2) is now available on the heroku-16 and heroku-18 stacks.
Several updated defaults apply to PHP 7.4 on Heroku. Customers are encouraged to thoroughly test their applications before upgrading.
Regular expressions for the mbstring multi-byte string extension (based on libonig) are disabled for PHP 7.4 at this time.
The cassandra extension is currently incompatible with PHP 7.4; all other extensions are available.
Customers wishing to remain on PHP 7.3 are reminded of the appropriate version selection mechanism available.
For a full list of changes in PHP 7.4, refer to the release announcement for PHP 7.4.0, and the PHP 7.4 upgrading guide on the official PHP website.