React Native DevTools Fails to Open on Fresh Install: `TypeError: fetch failed`

[aabuhijleh]

Description

I can't open React Native DevTools on a fresh install using the latest version.

I'm getting the following error

Failed to open the React Native DevTools.
TypeError: fetch failed

And I'm not the only one facing this issue. See react-native-community/discussions-and-proposals#819 (comment)

Steps to reproduce

Here's a repo where I can reproduce this issue 100% of the time: https://github.com/aabuhijleh/fresh-start

# init app
$ npx create-expo-app@latest

# use development build (or don't; same issue)
$ npm install expo-dev-client

# install and run the app on android emulator (or physical device, or ios; same issue)
$ npm run android

Then after pressing j, the dev tools won't open and you get an error message instead.

React Native Version

0.76.5

Output of npx react-native info

System:
  OS: macOS 15.1.1
  CPU: (11) arm64 Apple M3 Pro
  Memory: 174.23 MB / 18.00 GB
  Shell:
    version: 3.7.1
    path: /opt/homebrew/bin/fish
Binaries:
  Node:
    version: 20.17.0
    path: ~/.local/share/nvm/v20.17.0/bin/node
  Yarn:
    version: 1.22.22
    path: /opt/homebrew/bin/yarn
  npm:
    version: 10.8.2
    path: ~/.local/share/nvm/v20.17.0/bin/npm
  Watchman:
    version: 2024.12.02.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.16.2
    path: /opt/homebrew/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 24.2
      - iOS 18.2
      - macOS 15.2
      - tvOS 18.2
      - visionOS 2.2
      - watchOS 11.2
  Android SDK: Not Found
IDEs:
  Android Studio: 2024.1 AI-241.19072.14.2412.12360217
  Xcode:
    version: 16.2/16C5032a
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.13
    path: /usr/bin/javac
  Ruby:
    version: 2.6.10
    path: /usr/bin/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 15.1.3
    wanted: ^15.1.3
  react:
    installed: 18.3.1
    wanted: 18.3.1
  react-native:
    installed: 0.76.5
    wanted: 0.76.5
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: true
  newArchEnabled: true

Screenshots and Videos

React.Native.DevTools.Issue.mp4

[aabuhijleh]

I believe this is an issue with the expo cli. So I'm opening it there #48384

[ground-beetle]

@aabuhijleh I guess wrong link 😄 You meant this one