React devtools 4.0.4 (8/18/2019) Expected to find root ID

[techird]

Do you want to request a feature or report a bug?

a bug

What is the current behavior?

The new dev tools is deprecating react 0.14 in a breaking way.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem. Your bug will get fixed much faster if we can run your code and it doesn't have dependencies other than React. Paste the link to your JSFiddle (https://jsfiddle.net/Luktwrdm/) or CodeSandbox (https://codesandbox.io/s/new) example below:

Reference to react-devtools#1388, the stack:

It happend when you try to unmount element in React 14.

What is the expected behavior?

Just give a dprecated warning instead of breaking the runtime.

Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?

React 0.14.7

[MonstraG]

Can confirm, React 0.14.0.

[zasuh]

Can also confirm, React 0.14.0

[kunukn]

Breaking change.

Which versions of React are supported?
react-dom

0-14.x: Not supported
15.x: Supported (except for the new component filters feature)
16.x: Supported
react-native

0-0.61: Not supported
0.62: Will be supported (when 0.62 is released)

https://reactjs.org/blog/2019/08/15/new-react-devtools.html#which-versions-of-react-are-supported

[bvaughn]

As @kunukn mentioned, the new DevTools does not support React v14 and older. This was mentioned in the blog post along with instructions on how to install the previous version of the DevTools.

I apologize for the inconvenience here. We're a small team and we really only have one or two people working on DevTools most of the time. Since version 15 has been out for over 3 years, we made a pragmatic decision to only invest in supporting v15 and newer.

Thanks for understanding.

[bvaughn]

To clarify: I closed this issue because we don't intend to add v14 support.

However, we do plan to improve the v14 experience by showing a notification (rather than just throwing). That work is covered in #16462.

[prasanthLalapeta]

Deprecated warning will be good instead of code breaks :)

[pinkdoremi]

If you won't support v14, you can just show me an Error just like 'not support any more'. But now, it breaks my projects.
I use react in many projects vary from v14 to 16.7. The only way for me to debug the v14 project is to disable the React devtools temporarily.

[bvaughn]

As mentioned two comments above yours, @pinkdoremi

we do plan to improve the v14 experience by showing a notification (rather than just throwing). That work is covered in #16462.

[bibblebabl]

Same. "react": "^0.14.6"

[gaearon]

I'll lock this because "+1"s are not helpful and don't add any new information. In case you've missed the reply: #16500 (comment)

TLDR:

• 0.14 is not supported in the new DevTools
• If you need 0.14 support, build old DevTools from source and keep using them as long as you like: https://reactjs.org/blog/2019/08/15/new-react-devtools.html#how-do-i-get-the-old-version-back

We'll add a better error message in the future.

Hope this helps!