Web request callback raised an exception (ArgumentNullException: Value cannot be null.
Parameter name: key)
  at System.Collections.Generic.Dictionary`2[TKey,TValue].TryInsert (TKey key, TValue value, System.Collections.Generic.InsertionBehavior behavior) [0x00008] in <fb001e01371b4adca20013e0ac763896>:0

  at System.Collections.Generic.Dictionary`2[TKey,TValue].Add (TKey key, TValue value) [0x00000] in <fb001e01371b4adca20013e0ac763896>:0

  at Oxide.Plugins.ServerArmour.AddPlayerCached (Oxide.Plugins.ServerArmour+ISAPlayer isaplayer) [0x0000c] in <e784b25e9ef84da8946f8e18e74f0b0f>:0

  at Oxide.Plugins.ServerArmour+<_webCheckPlayer>c__AnonStorey1.<>m__0 (System.Int32 code, System.String response) [0x00137] in <e784b25e9ef84da8946f8e18e74f0b0f>:0

  at Oxide.Core.Libraries.WebRequests+WebRequest.<OnComplete>b__42_0 () [0x00034] in <bae5f1223fce49c493b01571c99dce02>:0

Same for me