Why I am getting all errors as "is not valid" ?(v3)

[toshi-ue]

I found a similar question below.
Why I am getting all errors as "is not valid" ? · Discussion #3999 · logaretm/vee-validate

I use "vue": "^2.5.17" and "vee-validate": "^3.4.14", but it didn't work. so let me ask you a question.
I tried to make myapp localization and set it according to documentation.
Localization | VeeValidate

But the message always says is not valid.
Please tell me the solution.
The code is below.

<template>
  <div>
    <ValidationObserver ref="observer" v-slot="{ invalid }">
        <form v-on:submit.prevent="submit">
                <ValidationProvider rules="required|min:3|max:8" v-slot="{ errors }">
                    <textarea class="col-sm-9 form-control" id="description"
                        v-model="task.description" rows="2" autofocus />
                    <span class="text-danger">{{ errors[0] }}</span>
                </ValidationProvider>
        </form>
    </ValidationObserver>
  </div>
</template>

<script>
import { ValidationObserver, ValidationProvider, extend, localize } from "vee-validate";
import en from "vee-validate/dist/locale/en.json";
import { max, min, required } from "vee-validate/dist/rules";

localize('en')

extend("max", max);
extend("min", min);
extend("required", required);

export default {
  components: {
      ValidationObserver,
      ValidationProvider,
  },
}
</script>

[toshi-ue]

answer is applied by logaretm.
Thank you!!
Why I am getting all errors as "is not valid" ?(v3) · Issue #4010 · logaretm/vee-validate