HHVM 4.93 is released! This release marks the end of support for 4.84; HHVM 4.86–4.92 remain supported, as do the 4.56 and 4.80 LTS releases.

(Note: HHVM 4.85, 4.89 and 4.90 were skipped.)


  • New feature: Contexts and Capabilities
    • The hhconfig flags enable_coeffects_syntax, call_coeffects, local_coeffects, and the INI option hhvm.hack.lang.enable_coeffects can be used to enabled this feature in recent HHVM versions, or to disable this feature in HHVM 4.93.
  • Improved typechecker handling of subtyping with generic type parameters. Some programs that were previously rejected despite being correct, now pass (example).

Breaking Changes

  • Accessing an undefined property on an object now throws an UndefinedPropertyException at runtime (previously only a notice). It had already been a typechecker error.