Not sure what i am missing

Failed to call hook 'Unload' on plugin 'SurvivalArena v1.0.3' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.SurvivalArena.EndEvent (System.Boolean unloaded) [0x001e2] in <561f288e10cb4540a56e717f3d72d1bc>:0 
  at Oxide.Plugins.SurvivalArena.Unload () [0x00007] in <561f288e10cb4540a56e717f3d72d1bc>:0 
  at Oxide.Plugins.SurvivalArena.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00155] in <561f288e10cb4540a56e717f3d72d1bc>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <09575a60985045248bcb43b20faeeb99>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <bae5f1223fce49c493b01571c99dce02>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <bae5f1223fce49c493b01571c99dce02>:0 
Web request produced exception (Url: https://www.dropbox.com/s/iylthpdq1witbl8/Arena.json?dl=1) in 'SurvivalArena v1.0.3' plugin (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Core.Libraries.WebRequests+WebRequest.<WaitForResponse>b__40_0 (System.IAsyncResult res) [0x00000] in <bae5f1223fce49c493b01571c99dce02>:0 

Get this why i try to do an install

Do you have EventHelper plugin installed?

thank you that was what i missed...

Changed Status from Pending to Closed