Essentials for Bukkit has been discontinued.
That means there is no updates for 1.8/1.9 or any future versions of 'Bukkit' or Spigot.
We will never again update Essentials for Bukkit. The project is closed, the development team has moved on.
Since there isn't an Essentials for 1.8/1.9+, there is no support.
Since Bukkit was taken down by DMCA, there have been a few websites pretending to release Bukkit for 1.8/1.9+
These aren't official versions, and not supported by the majority of developers.
In the vacuum created by Bukkit's departure, Sponge as come to fill the gap.
Sponge is like Bukkit, but supports modded servers natively, and was built by the major developers behind Bukkit, Forge, and Bukkit plugins.