HHVM 4.84 is released! This release marks the end of support for 4.78; HHVM 4.79–4.82 remain supported, as does the 4.56 LTS release. This primarily contains internal improvements for performance, maintainability, and preparation for future work.

We will not be releasing 4.85 next week due to US holidays; we expect the next release to be 4.86, during the week of 2020-11-30.


  • Fixed propagation of reified generics in class B<T> extends A<T> when A’s T parameter is reified, but B’s is not.

Future Changes

  • Indexing into a string with an index that is not an arraykey will throw an InvalidArgumentException; currently, it emits a String offset cast occurred notice.