Cannot set property 'innerHTML' of undefined

[CaiPeng1989]

Version

3.0.0-alpha.2

Reproduction link

https://codepen.io/caipeng1989/pen/YzPJbbm

Steps to reproduce

const {
  createApp,
  defineComponent
} = Vue

const App = defineComponent({
  template: `<div>app</div>`
})

createApp(App).mount('#app')

What is expected?

Render correctly

What is actually happening?

TypeError: Cannot read property 'innerHTML' of undefined

[underfin]

You should run createApp().mount(App, '#app')

[CaiPeng1989]

createApp().mount(App, '#app')

The default code is like this.
But, Global API Change said:

import { createApp } from 'vue'
import App from './App.vue'

const app = createApp(App)

app.config.ignoredElements = [/^app-/]

app.use(/* ... */)
app.mixin(/* ... */)
app.component(/* ... */)
app.directive(/* ... */)

app.mount('#app')

[underfin]

Year.The implementation has diffrent with sfc.

[CaiPeng1989]

So we need to write code like this:

import { createApp } from 'vue'
import App from './App.vue'

const app = createApp()

app.config.ignoredElements = [/^app-/]

app.use(/* ... */)
app.mixin(/* ... */)
app.component(/* ... */)
app.directive(/* ... */)

app.mount(App, '#app')

[underfin]

Yea.It is works for current master code.

[posva]

The up to date version is at rfcs: https://github.com/vuejs/rfcs/blob/master/active-rfcs/0009-global-api-change.md

[yyx990803]

The RFC PR had outdated summary (fixed)