- Phabricator supports PHP 7.1 and newer, but this support is new (circa January 2017) and less thoroughly tested than PHP 5, so you may encounter some issues.
- Phabricator does not support PHP 7.0 through PHP 7.1. A feature Phabricator relies on (asynchronous signal handling) was removed in PHP 7.0 and not made available again until PHP 7.1.
- PHP7 support is not available in versions of Phabricator earlier than 2017 Week 2.
- You should install OpCache to provide bytecode caching.
- You should install APCu (version 5.x.x) to provide data caching.