Change effective on 10 February 2020
PHP 7.4 (release 7.4.2) is now available on the
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.
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.