EAS Build failing at Prebuild phase — EACCES permission denied on .expo/web

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Summary

Hi everyone,

I've been stuck on this issue for several hours and can't figure out what's causing it. I'm building a React Native app with Expo SDK 54 and every time I run an EAS Build for iOS, it fails at the Prebuild phase with the same error.

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My Setup:

• Expo SDK: 54.0.33
• React Native: 0.81.5
• EAS CLI: latest
• Platform: iOS (internal distribution / preview profile)
• Building from: Windows 11 (PowerShell)

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The Error:

Error: [ios.dangerous]: withIosDangerousBaseMod: EACCES: permission denied, mkdir '/Users/expo/workingdir/build/.expo/web'

npx expo prebuild --no-install --platform ios exited with non-zero code: 1

The full stack trace points to:

at async ensureCacheDirectory (@expo/image-utils/build/Cache.js:40:5)
at async generateImageAsync (@expo/image-utils/build/Image.js:227:22)
at async generateUniversalIconAsync (...withIosIcons.js:187:15)

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What I've already tried:

1. Updated @expo/image-utils to latest
2. Removed the web section from app.json
3. Removed expo-web-browser from the plugins array in app.json
4. Added EXPO_IMAGE_UTILS_NO_SHARP: "1" to the env in eas.json
5. Added overrides in package.json to force a single version of @expo/image-utils
6. Deleted node_modules and package-lock.json and ran a clean npm install
7. Ran every build with --clear-cache

None of these fixed it. The error is always identical.

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What expo doctor says:

Found duplicates for expo-constants:
- expo-constants@18.0.13 (node_modules/expo/node_modules/expo-constants)
- expo-constants@18.0.13 (node_modules/expo-auth-session/node_modules/expo-constants)
- expo-constants@18.0.13 (node_modules/expo-linking/node_modules/expo-constants)

Though it's the same version across all three, so I'm not sure this is causing the issue.

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My current eas.json:

{
  "cli": { "version": ">= 18.4.0", "appVersionSource": "remote" },
  "build": {
    "preview": {
      "distribution": "internal",
      "env": {
        "EXPO_IMAGE_UTILS_NO_SHARP": "1"
      }
    }
  }
}

My current app.json plugins:

"plugins": ["expo-font"]

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My understanding of the root cause:
It seems like @expo/image-utils is trying to create a cache directory at .expo/web on the EAS build server, but the process doesn't have write permissions to that path. This happens regardless of what I change locally, which makes me think it's something in how EAS sets up the build environment for SDK 54.

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My question:
Has anyone encountered this exact error with Expo SDK 54 on EAS Build? Is there a known fix or workaround? I've seen suggestions about eas-build-post-install hooks — would that help here, and if so, what exactly should it contain?

Any help would be greatly appreciated!

Link to the related documentation page

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