HHVM 4.123 is released! This release marks the end of support for 4.117; HHVM 4.118–4.122 remain supported, as do the 4.80 and 4.102 LTS releases.


  • Improved typechecker error messages when refining objects to a class that doesn’t exist.
  • Indexing containers with covariant keys now results in a distinct, clearer, error (4449) if the key type is incompatible. Some FIXMes may need changing.
  • LSP-based IDEs may now suggest quickfixes when calling typoed static/instance methods.

Breaking Changes

  • Arguments to meth_caller() must now be constants