Did you run it on HHVM? That class is implemented in HHVM <a href="https:&#x2F;&#x2F;docs.hhvm.com&#x2F;hack&#x2F;reference&#x2F;class&#x2F;AsyncMysqlConnectionPool&#x2F;" rel="nofollow">https:&#x2F;&#x2F;docs.hhvm.com&#x2F;hack&#x2F;reference&#x2F;class&#x2F;AsyncMysqlConnect...</a>