.net core 2.0 System.Runtime higher

[winkey0428]

Error CS1705 "System.Runtime, Version=4.2.1.0, Culture" used by assembly "Alachisoft.NCache.CoreSessionStoreProvider" identified as "Alachisoft.NCache.CoreSessionStoreProvider, Version=5.0.0.0, Culture=neutral, PublicKeyToken=1448e8d1123e9096" =neutral, PublicKeyToken=b03f5f7f11d50a3a" version is higher than the referenced assembly "System.Runtime" identified as "System.Runtime, Version=4.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" WebApplication1 C:\Users\ThinkPad\ Desktop\WebApplication1\WebApplication1\CSC 1 Activity