@ioncoder your snippet were not showing what your state looks like before you were trying to mutate it so, it’s not also showing whether your function is really a vuex mutation function (you need to provide sufficient info next time.), you’ll need further reading into vue reactivity itself https://vuejs.org/v2/guide/reactivity.html#Change-Detection-Caveats. the one from vuex works because count already exist in the state object.