[vuex] unknown mutation type / unknown action type Vue Origin: On your device OSI layer 7 · Application Last updated 5 Nov 2026

Vuex: [vuex] unknown mutation type: SET_USER / [vuex] unknown action type: fetchUser

commit/dispatch was called with a name that isn't registered in the store (or its module namespace).

Exact message you may see [vuex] unknown mutation type: SET_USER[vuex] unknown action type: fetchUser[vuex] unknown getter: x[vuex] module namespace not found in mapState(): user/unknown mutation type
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Seen on: Vue

Meaning

Check the exact name, module namespacing (user/SET_USER when namespaced: true), that the module is registered, and typos. In components mapMutations("user", [...]) helps. Vuex 3/4 is legacy; Pinia is the recommended store.

Common causes

  • Typo in mutation/action name
  • Namespaced module needs module/name
  • Module not registered
  • Calling mutation via dispatch (or reverse)
  • Hot-reload dropping modules

⚡ Quick fix

  1. Use store.commit("user/SET_USER", payload) for namespaced modules
  2. Register modules in new Vuex.Store({ modules: { user } })
  3. Verify names with Vue devtools

Detailed fix by platform

Vue

  1. this.$store.commit("user/SET_USER", user)

How to diagnose

  1. Name — Exact?
  2. Namespace — Prefixed?
  3. Module — Registered?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: On your device. Errors that are often confused with or caused by this one (click to open):

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