We have decided to cancel next week’s release of HHVM 4.37, and expect to delay 4.38 until Thursday, the 2nd of January. HHVM 4.31 will be supported until the release of HHVM 4.38 or above. As HHVM 4.32 has long-term-support (LTS), it is unaffected by this change.
Our usual schedule is to release on Mondays or Tuesdays, and we expect many people - both at Facebook, and among our users - to be on vacation for Tuesday and Wednesday for the next two weeks. We believe that releasing new versions with breaking changes at this time would not be in the best interests of our users, especially as we would be less able to support them during this time.
We look forward to continuing the evolution of Hack and HHVM in 2020.