Hi! I checked the version. So i was on 2.5.8, i updated to 2.5.8.1 and the warning persist but i noticed a new information about it:
SendMessage cannot be called during Awake, CheckConsistency, or OnValidate
UnityEngine.MeshFilter:set_sharedMesh(Mesh)
tk2dSprite:OnValidate() (at Assets/TK2DROOT/tk2d/Code/Sprites/tk2dSprite.cs:118)
UnityEditor.PrefabUtility:InstantiatePrefab(Object)
tk2dRuntime.TileMap.BuilderUtil:SpawnPrefabsForChunk(tk2dTileMap, SpriteChunk, Int32, Int32, Int32, Int32[]) (at Assets/TK2DROOT/tk2dTileMap/Code/tk2dTileMapBuilderUtil.cs:128)
tk2dRuntime.TileMap.BuilderUtil:SpawnPrefabs(tk2dTileMap, Boolean) (at Assets/TK2DROOT/tk2dTileMap/Code/tk2dTileMapBuilderUtil.cs:202)
tk2dTileMap:Build(BuildFlags) (at Assets/TK2DROOT/tk2dTileMap/Code/tk2dTileMap.cs:326)
tk2dTileMap:Awake() (at Assets/TK2DROOT/tk2dTileMap/Code/tk2dTileMap.cs:121)
UnityEngine.Object:Instantiate(GameObject)
SceneController:changeMap(GameObject, Boolean) (at Assets/Scripts/proto_scripts/SceneController.cs:117)
<goMap>c__Iterator3:MoveNext() (at Assets/Scripts/proto_scripts/SceneController.cs:93)
UnityEngine.SetupCoroutine:InvokeMoveNext(IEnumerator, IntPtr)
it seems that the problem come from one of my scripts when i try to instanciate a tilemap from ressources :-p i know now it is very bad to do like this but i'am a very very noob coder :-p
i have to modify this part to use assetbunble instead as it is recommended. but i don't know if it will correct anything about the warning. to be sure, i also tried to open again the project on unity 5.6 and (except some asserts from migration) the warning disappear ;( ...