[cranekam]

Facebook doesn't run vanilla PHP. It runs on Hack, a language developed from PHP that runs on HHVM, a JIT VM it developed:

https://engineering.fb.com/developer-tools/hack-a-new-progra...

[throwaway40324]

Right, but up until after Hackv3.3, PHP code was supported, which support ended 9 days ago.

"HHVM v3.30 will be the last release series where HHVM aims to support PHP. The key dates are...

2019-11-19: expected end of support for v3.30"

https://hhvm.com/blog/2018/09/12/end-of-php-support-future-o...

Note: I really dont believe my above speculation is related, just thought it was an interesting coincidence, at best.