diff --git a/Mirror/Runtime/NetworkManager.cs b/Mirror/Runtime/NetworkManager.cs
index 6cfdf694f..aa7936bc2 100644
--- a/Mirror/Runtime/NetworkManager.cs
+++ b/Mirror/Runtime/NetworkManager.cs
@@ -58,6 +58,15 @@ public class NetworkManager : MonoBehaviour
         public virtual void Awake()
         {
             Debug.Log("Thank you for using Mirror! https://forum.unity.com/threads/mirror-networking-for-unity-aka-hlapi-community-edition.425437/");
+
+            if (Application.unityVersion.CompareTo("2018.3") >= 0)
+            {
+                Debug.LogError(
+                    "This version of mirror is not compatible with Unity 2018.3 and up. " +
+                    "Please use unity 2017.4, 2018.1, 2018.2 or use the 2018 mirror branch " +
+                    "https://github.com/vis2k/Mirror/tree/2018");
+            }
+
             InitializeSingleton();
         }