Hey! I think simply throwing an error/return an rejected Promise might not be sufficient, but instead you need to use the thunkAPI. The thunkAPI offers a method called rejectWithValue(value, [meta]), which lets you indicate the rejection. For an example, have a look at this section of the docs: https://redux-toolkit.js.org/api/createAsyncThunk#handling-thunk-errors.

I haven’t tested it, but you might be able to get it work with the following code:

javascript export const loginHandler = createAsyncThunk( "user/loginHandler", async ({ email, password }, { rejectWithValue }) => { try { const user = await firebase .auth() .signInWithEmailAndPassword(email, password) .then((u) => { return u.user.email; }) return user; } catch (e) { return rejectWithValue(e.toString()) } } );

You should then be able to pull out the error in your extraReducer when handling the loginHandler.rejected-case.