Repository: react-native
Issue: Can't fetch the source map while using the experimental debugger
Labels: 🌐Networking,Debugger,Newer Patch Available,Resolution: Answered

### Description

I'm trying to use the new experimental debugger in our RN project, but in the DevTool window it says this:
> Failed to fetch source map http://10.39.25.45:8081/index.map?platform=ios&dev=true&lazy=true&minify=false&inlineSourceMap=false&modulesOnly=false&runModule=true&app=com.teslamotors.enterpriseapp: remote fetches not permitted

and can't fetch the source map, thus no source code is shown.

Here're some interesting I've found:
- I can access this URL in Safari and in CLI using `wget` and `curl`, but I got this when I open it in Chrome:
<img width="1907" alt="image" src="https://github.com/user-attachments/assets/1e34d550-0b35-4d24-9f78-444326620db5">

- I noticed this using Chrome's dev tools:

https://github.com/user-attachments/assets/54f9a1d7-cc13-4b0f-a2ce-30dd38225ce6

The "content download" always gets killed after around 3.5s, and then it becomes "Aw Snap!"
- I tried to use the experimental debugger on the Expo tutorial's starter app, which works fine (I think it's using the experimental debugger, instead of the old one?)
- Our source map has ~200MB size

My assumption is that because our source map is so big, Chrome isn't able to download it within a time limit (so the download is always canceled after 3.5s) but I have no idea of how to verify that. Not sure if this is a Chrome bug or RN bug but I'll post it here anyway.

### Steps to reproduce

Just launch the experimental debugger on some huge app with ~200MB source map, I guess?

### React Native Version

0.73.6

### Affected Platforms

Build - MacOS

### Output of `npx react-native info`

```text
npx react-native info

  WARNING: You should run npx react-native@latest to ensure you're always using the most current version of the CLI. NPX has cached version (0.73.6) != current release (0.75.2)

info Fetching system and libraries information...
System:
  OS: macOS 14.5
  CPU: (12) arm64 Apple M3 Pro
  Memory: 807.53 MB / 36.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 18.12.0
    path: /usr/local/bin/node
  Yarn:
    version: 1.22.22
    path: /opt/homebrew/bin/yarn
  npm:
    version: 8.19.2
    path: ~/.nvm/versions/node/v18.12.0/bin/npm
  Watchman:
    version: 2024.07.15.00
    path: /usr/local/bin/watchman
Managers:
  CocoaPods:
    version: 1.15.2
    path: /Users/kainzhong/.rbenv/shims/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 23.2
      - iOS 17.2
      - macOS 14.2
      - tvOS 17.2
      - watchOS 10.2
  Android SDK: Not Found
IDEs:
  Android Studio: 2024.1 AI-241.15989.150.2411.11948838
  Xcode:
    version: 15.1/15C65
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.11
    path: /usr/bin/javac
  Ruby:
    version: 2.7.5
    path: /Users/kainzhong/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 18.2.0
    wanted: 18.2.0
  react-native:
    installed: 0.73.6
    wanted: 0.73.6
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: false
iOS:
  hermesEnabled: true
  newArchEnabled: false

info React Native v0.75.2 is now available (your project is running on v0.73.6).
info Changelog: https://github.com/facebook/react-native/releases/tag/v0.75.2
info Diff: https://react-native-community.github.io/upgrade-helper/?from=0.75.2
info For more info, check out "https://reactnative.dev/docs/upgrading?os=macos".
```


### Stacktrace or Logs

```text
> Failed to fetch source map http://10.39.25.45:8081/index.map?platform=ios&dev=true&lazy=true&minify=false&inlineSourceMap=false&modulesOnly=false&runModule=true&app=com.teslamotors.enterpriseapp: remote fetches not permitted
```


### Reproducer

I really don't know how to reproduce this on smaller projects

### Screenshots and Videos

Included some in the description.