I just got 1.9 and i installed the 1.9 versions of essentials and it gives me this error:
[20:18:17 INFO]: CONSOLE: Please note that this command is not supported and may cause issues when using some plugins.

[20:18:17 INFO]: CONSOLE: If you encounter any issues please use the /stop command to restart your server.

[20:18:17 INFO]: [Essentials] Loading Essentials vTeamCity

[20:18:17 INFO]: [EssentialsChat] Loading EssentialsChat vTeamCity

[20:18:17 INFO]: [EssentialsSpawn] Loading EssentialsSpawn vTeamCity

[20:18:17 INFO]: [Essentials] Enabling Essentials vTeamCity

[20:18:17 INFO]: Bukkit version format changed. Version not checked.

[20:18:17 INFO]: git-Bukkit-18fbb24 (MC: 1.8.8)

[20:18:17 INFO]: 1.8.8-R0.1-SNAPSHOT

[20:18:17 INFO]: Creating config from template: /Users/stijnsimons/Downloads/Minecraft Bukkit Server/Minecraft Bukkit Server/plugins/Essentials/config.yml

[20:18:17 ERROR]: java.lang.NoSuchMethodError: java.nio.CharBuffer.subSequence(II)Ljava/nio/CharBuffer;

[20:18:17 ERROR]: Error occurred while enabling Essentials vTeamCity (Is it up to date?)

java.lang.NullPointerException

at com.earth2me.essentials.Essentials.onDisable(Essentials.java:348) ~[?:?]

at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:323) ~[craftbukkit.jar:git-Bukkit-18fbb24]

at com.earth2me.essentials.Essentials.handleCrash(Essentials.java:747) ~[?:?]

at com.earth2me.essentials.Essentials.onEnable(Essentials.java:275) ~[?:?]

at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:321) ~[craftbukkit.jar:git-Bukkit-18fbb24]

at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:332) [craftbukkit.jar:git-Bukkit-18fbb24]

at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:404) [craftbukkit.jar:git-Bukkit-18fbb24]

at org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugin(CraftServer.java:342) [craftbukkit.jar:git-Bukkit-18fbb24]

at org.bukkit.craftbukkit.v1_8_R3.CraftServer.enablePlugins(CraftServer.java:314) [craftbukkit.jar:git-Bukkit-18fbb24]

at org.bukkit.craftbukkit.v1_8_R3.CraftServer.reload(CraftServer.java:720) [craftbukkit.jar:git-Bukkit-18fbb24]

at org.bukkit.Bukkit.reload(Bukkit.java:544) [craftbukkit.jar:git-Bukkit-18fbb24]

at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:25) [craftbukkit.jar:git-Bukkit-18fbb24]

at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:140) [craftbukkit.jar:git-Bukkit-18fbb24]

at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchCommand(CraftServer.java:620) [craftbukkit.jar:git-Bukkit-18fbb24]

at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchServerCommand(CraftServer.java:606) [craftbukkit.jar:git-Bukkit-18fbb24]

at net.minecraft.server.v1_8_R3.DedicatedServer.aO(DedicatedServer.java:372) [craftbukkit.jar:git-Bukkit-18fbb24]

at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:336) [craftbukkit.jar:git-Bukkit-18fbb24]

at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:629) [craftbukkit.jar:git-Bukkit-18fbb24]

at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:537) [craftbukkit.jar:git-Bukkit-18fbb24]

at java.lang.Thread.run(Thread.java:695) [?:1.6.0_65]

[20:18:17 INFO]: [EssentialsChat] Enabling EssentialsChat vTeamCity

[20:18:17 INFO]: [EssentialsSpawn] Enabling EssentialsSpawn vTeamCity

[20:18:17 INFO]: Server permissions file permissions.yml is empty, ignoring it

I hope you could help.
More info:
I'm using macOSX
Bukkit version:
[20:24:05 INFO]: This server is running CraftBukkit version git-Spigot-0426685-4cd46b2 (MC: 1.9) (Implementing API version 1.9-R0.1-SNAPSHOT)
Thanks