Phabricator currently does not support PHP 7. There are two major known issues:
- Opcode and data caches (APC, APCu, OpCache, APCu_bc) have changed, and we do not yet provide guidance about how to install or configure them.
- PHP 7 does not support asynchronous signal handling until a future (currently unreleased) version. See T11270 for details.
The new async_signals proposal may be available in PHP 7.1. We will re-evaluate support after it is available.