Vuetify Menu not working: Property or method “on” is not defined on the instance but referenced during render

问题

I am copying an first example from the official documentation Vuetify about Menus, but the result is an error :

"Property or method "on" is not defined on the instance but referenced during render".

<template>
        <v-app>
            <div class="text-xs-center">
                <v-menu offset-y>
                    <template v-slot:activator="{ on }">
                        <v-btn
                                color="primary"
                                dark
                                v-on="on"
                        >
                            Dropdown
                        </v-btn>
                    </template>
                    <v-list>
                        <v-list-tile
                                v-for="(item, index) in items"
                                :key="index"
                                @click=""
                        >
                            <v-list-tile-title>{{ item.title }}</v-list-tile-title>
                        </v-list-tile>
                    </v-list>
                </v-menu>
            </div>
        </v-app>
    </template>
    
    <script>
        export default {
            data: () => ({
                items: [
                    { title: 'Click Me' },
                    { title: 'Click Me' },
                    { title: 'Click Me' },
                    { title: 'Click Me 2' }
                ]
            })
        }
    </script>

回答1:

I had the same issue in Vuetyfy 1.4.4 and Vue 2.5. Updating this packages fixed problem. In vue 2.6.9 and vuetify 1.5.6 attribute v-slot:activator="{ on }" works great. Check your outdated packages by npm outdated --depth=0 and then update them by npm update vuetyfy vue etc.

来源：https://stackoverflow.com/questions/55136999/vuetify-menu-not-working-property-or-method-on-is-not-defined-on-the-instance