Why does React hot-reloading on Firefox automatically open the Debugger?

Viewed 1178
  • OS: MacOS Catalina 10.15.5
  • Browser: Firefox 78.0.2 with React Developer Tools 4.8.0 add-on enabled
  • IDE: Visual Studio Code 1.46.1
  • Framework: React

This all of a sudden started happening today. Maybe Firefox updated in the background without me knowing, but one minute this never happened, and now it won't stop happening.

Problem: Whenever I save a local file I am working on that has a React error (could be a missing component prop, or improper syntax), Firefox reloads the page but then directs me to the Debugger DevTools tab, and pauses the page. I then have to navigate back to the Console DevTools tab, and manually reload the page. It's very frustrating.

When the browser re-directs to the Debugger, there is a dialogue on the page saying "Paused on debugger statement". The highlighted debugger code is:

// --- Welcome to debugging with React DevTools ---
// This debugger statement means that you've enabled the "break on warnings" feature.
// Use the browser's Call Stack panel to step out of this override function-
// to where the original warning or error was logged.
// eslint-disable-next-line no-debugger
debugger;t.apply(void 0,o)};n.__REACT_DEVTOOLS_ORIGINAL_METHOD__=t,// $FlowFixMe property error|warn is not writable.

The only way to stop this is to disable the React Developer Tools add-on. I don't know how to disabled the "break on warnings" feature. Any help would be deeply appreciated.

===

Edit: I looked at the React Developer Tools Profiler tab, went to Settings, then Debugging, and noticed that the "Break on warnings" was already unchecked. Still unsure what the solution could be.

2 Answers

It's a bug from the latest React Dev Tools (4.8.0): https://github.com/facebook/react/issues/19308

Workaround is to toggle the Break on Warnings setting on and then off. They've already cut a release (4.8.1) that fixes the problem.

I had the same issue. Toggling the setting on then off again fixed it.

Related