devtools: 5.3.2: Property or method "then" is not defined on the instance but referenced during render

I also get this error, but only when i enable “New Vuex backend” in settings. When i disable this setting, the error does not appear.

Hello!

My case for reproducing

You need app that uses following packages:

1. Vue Router
2. Vuex
3. vuex-router-sync

App should have minimum two routes =)

Steps:

1. Open your app in browser
2. Open Vue developer tools
3. Navigate to other app page (route)
4. vuex-router-sync runs mutation route/ROUTE_CHANGED with payload {from, to} where will have references to components and their instances
5. Vue developer runs cloning of mutation payload and instances of Vue components
6. When devtools try to clone payload.to.matched.0.instances.default._renderProxy Proxy checks the availability of method then and shows warning

<del>I think this might be related to using import to load components.</del> I’ll try to add a minimal example.

I nailed it 😃

Code here: https://codesandbox.io/s/vue-routing-example-zj1so With reproduction link here: https://zj1so.csb.app/hello

Please open chrome dev tools, switch to Vue tab and check “New vuex backend” is enabled, then switch to console tab and do a refresh.

Just wanted to say I’ve been debugging my app for 2 hours so thank you @nicooprat for this issue! 😞 🙌

同时存在两个不同版本的vue-devtools，禁用调其中一个就OK了

Getting this error in version 6.0.0 beta 19 #1583

Please provide a runnable minimal reproduction.