Unity錯誤——1.error CS1704: An assembly with the same name `UnityEngine.UI' has already been imported._unity

今天在使用Unity5.5.0時，開啟昨天的Unity 工程出現如下錯誤：

1.error CS1704: An assembly with the same name `UnityEngine.UI' has already been imported. Consider removing one of the references or sign the assembly2./Applications/Unity 5.5 navmesh/Unity navmesh.app/Contents/UnityExtensions/Unity/GUISystem/UnityEngine.UI.dll (Location of the symbol related to previous error)3./Applications/Unity 5.5 navmesh/Unity navmesh.app/Contents/UnityExtensions/Unity/GUISystem/Standalone/UnityEngine.UI.dll (Location of the symbol related to previous error)4.error CS1704: An assembly with the same name `UnityEngine.Networking' has already been imported. Consider removing one of the references or sign the assembly5./Applications/Unity 5.5 navmesh/Unity navmesh.app/Contents/UnityExtensions/Unity/Networking/UnityEngine.Networking.dll (Location of the symbol related to previous error)6./Applications/Unity 5.5 navmesh/Unity navmesh.app/Contents/UnityExtensions/Unity/Networking/Standalone/UnityEngine.Networking.dll (Location of the symbol related to previous error)7.error CS1704: An assembly with the same name `UnityEngine.HoloLens' has already been imported. Consider removing one of the references or sign the assembly8./Applications/Unity 5.5 navmesh/Unity navmesh.app/Contents/UnityExtensions/Unity/UnityHoloLens/Runtime/UnityEngine.HoloLens.dll (Location of the symbol related to previous error)9./Applications/Unity 5.5 navmesh/Unity navmesh.app/Contents/UnityExtensions/Unity/UnityHoloLens/RuntimeEditor/UnityEngine.HoloLens.dll (Location of the symbol related to previous error)10. 

解決方案：

關閉當前工程； 刪除工程所在目錄的Library檔案夾 重啟工程，Unity講重新寫入相關Library，即可解決問題。