It seems you only upgraded your Spine editor version, but you have not upgraded your spine-unity runtime yet. Please upgrade your spine-unity runtime by following this guide:
Spine-Unity 4.0 to 4.1 Upgrade Guide
Or if your project needs to use spine-unity 4.0, then you need to downgrade your Spine project saved in 4.1 to 4.0. Please refer to my previous post here for an explanation of the steps in the downgrade process:
4.1.04 FFD keys breaking glitch