EAS Build fails due to unexpected '--platform' option passed to prebuildCommand

[J4cKr0y]

Build/Submit details page URL

https://expo.dev/accounts/j4ckr0y/projects/flouz/builds/80f0a894-78ea-4876-9b87-79648761f61b

Summary

Hi team,

I'm experiencing an issue with EAS Build that seems to be a bug in how prebuildCommand is executed. My build consistently fails during the Prebuild phase with an error indicating an unexpected --platform option.

Description of the problem:
I am running a build for the preview profile on the Android platform using the command:
eas build --profile preview --platform android

The build process successfully starts, but it fails during the Prebuild step. The logs show that EAS is attempting to run the prebuildCommand (npm run prebuild:preview) but is incorrectly appending the --platform android option to it, resulting in the following error:
npx expo npm run prebuild:preview --platform android exited with non-zero code: 1
unknown or unexpected option: --platform

This is unexpected behavior, as the prebuildCommand script itself, defined in package.json, does not expect this option. The script simply executes ts-node scripts/install-ads.js.

Expected Behavior:
The prebuildCommand (npm run prebuild:preview) should be executed by itself without any additional arguments from the eas build command. The --platform argument should only be used by the eas build command to determine the build environment, not passed down to the pre-build script.

EAS Build log URL:
https://expo.dev/accounts/j4ckr0y/projects/flouz/builds/80f0a894-78ea-4876-9b87-79648761f61b

Thank you for your help!

Managed or bare?

Managed Workflow

Environment

Environment:
EAS CLI Version: eas-cli/16.17.4 win32-x64
Expo SDK Version: 53.0.20
Node.js Version: node-v22.16.0
NPM Version: 11.4.2
Operating System: Windows 10 Pro

Error output

Build failed

npx expo npm run prebuild:preview --platform android exited with non-zero code: 1

Reproducible demo or steps to reproduce from a blank project

Steps to reproduce:

Set up a project with the provided package.json, eas.json, and install-ads.ts files.

Run the command eas build --profile preview --platform android.

Observe the build logs on the EAS dashboard. The build will fail during the "Prebuild" step with the mentioned error.

Relevant files:
Here are the contents of my relevant files to help you reproduce the issue.

eas.json
JSON

{
  "cli": {
    "version": ">= 16.9.0",
    "appVersionSource": "remote"
  },
  "build": {
    "development": {
      "developmentClient": true,
      "distribution": "internal",
      "prebuildCommand": "npm run prebuild:dev",
      "android": {
        "buildType": "apk"
      }
    },
    "preview": {
      "distribution": "internal",
      "prebuildCommand": "npm run prebuild:preview",
      "android": {
        "buildType": "apk"
      },
      "ios": {}
    },
    "production": {
      "autoIncrement": true,
      "prebuildCommand": "npm run prebuild:prod",
      "android": {
        "buildType": "app-bundle"
      }
    }
  },
  "submit": {
    "production": {}
  }
}

package.json
JSON

{
  "name": "flouz",
  "version": "1.0.0",
  "main": "index.js",
  "scripts": {
    "start": "expo start",
    "android": "expo run:android",
    "ios": "expo run:ios",
    "web": "expo start --web",
    "test": "jest --watchAll",
    "test:ci": "jest --coverage --watchAll=false",
    "test:single": "jest --watchAll=false",
    "prebuild:dev": "ts-node scripts/install-ads-dev.js",
    "prebuild:preview": "ts-node scripts/install-ads.js",
    "prebuild:prod": "ts-node scripts/install-ads.js"
  },
  "expo": {
    "doctor": {
      "reactNativeDirectoryCheck": {
        "listUnknownPackages": false
      }
    }
  },
  "dependencies": {
    "@expo/metro-runtime": "~5.0.4",
    "@expo/vector-icons": "^14.1.0",
    "@react-native-async-storage/async-storage": "2.1.2",
    "@react-native-picker/picker": "^2.11.1",
    "@react-navigation/bottom-tabs": "^7.3.17",
    "@react-navigation/native": "^7.1.8",
    "@react-navigation/native-stack": "^7.3.21",
    "@react-navigation/stack": "^7.3.1",
    "expo": "53.0.20",
    "expo-audio": "~0.4.8",
    "expo-auth-session": "~6.2.1",
    "expo-build-properties": "~0.14.8",
    "expo-crypto": "~14.1.5",
    "expo-file-system": "~18.1.9",
    "expo-network": "~7.1.5",
    "expo-status-bar": "~2.2.3",
    "expo-system-ui": "~5.0.10",
    "expo-web-browser": "~14.2.0",
    "firebase": "^11.10.0",
    "react": "19.0.0",
    "react-dom": "19.0.0",
    "react-native": "0.79.5",
    "react-native-gesture-handler": "~2.24.0",
    "react-native-reanimated": "~3.17.4",
    "react-native-safe-area-context": "5.4.0",
    "react-native-screens": "~4.11.1",
    "react-native-svg": "15.11.2",
    "react-native-web": "^0.20.0"
  },
  "devDependencies": {
    "@testing-library/react-native": "^13.2.0",
    "@types/jest": "^29.5.14",
    "@types/react": "~19.0.10",
    "jest": "~29.7.0",
    "jest-expo": "~53.0.9",
    "react-test-renderer": "19.0.0",
    "typescript": "~5.8.3"
  },
  "private": true
}

scripts/install-ads.ts
TypeScript

// scripts/install-ads.ts
import { execSync } from 'child_process';
import * as fs from 'fs';

console.log('🚀 Installation automatique de react-native-google-mobile-ads...');

try {
  // 1. Installer le package
  execSync('npm install react-native-google-mobile-ads', { stdio: 'inherit' });
  
  // 2. Installer expo-tracking-transparency si pas déjà fait
  execSync('npx expo install expo-tracking-transparency', { stdio: 'inherit' });
  
  // 3. Créer/modifier app.json pour les pubs
  const appJsonPath = './app.json';
  const appJson = JSON.parse(fs.readFileSync(appJsonPath, 'utf8'));
  
  // Ajouter la config AdMob
  if (!appJson['react-native-google-mobile-ads']) {
    appJson['react-native-google-mobile-ads'] = {
      android_app_id: process.env.ANDROID_ADMOB_APP_ID || "ca-app-pub-3940256099942544~1458002511",
      ios_app_id: process.env.IOS_ADMOB_APP_ID || "ca-app-pub-3940256099942544~4354046892",
      delay_app_measurement_init: true,
      user_tracking_usage_description: "Cette app utilise des données pour personnaliser les publicités."
    };
  }
  
  // Ajouter les plugins
  if (!appJson.expo.plugins) {
    appJson.expo.plugins = [];
  }
  
  // Plugin tracking
  const trackingPlugin = [
    'expo-tracking-transparency',
    {
      userTrackingPermission: 'Cette app utilise des données pour personnaliser les publicités.'
    }
  ];
  
  if (!appJson.expo.plugins.some(p => Array.isArray(p) && p[0] === 'expo-tracking-transparency')) {
    appJson.expo.plugins.push(trackingPlugin);
  }
  
  // Sauvegarder app.json
  fs.writeFileSync(appJsonPath, JSON.stringify(appJson, null, 2));
  
  console.log('✅ Configuration AdMob ajoutée à app.json');
  
} catch (error) {
  console.error('❌ Erreur lors de l\'installation:', error.message);
  process.exit(1);
}

[J4cKr0y]

Issue Resolved: EAS Build --platform Argument Error

---

The build failure was successfully resolved by adding a simple argument filter at the beginning of the prebuild script.

Root Cause:
EAS Build was incorrectly passing the --platform android argument to our custom prebuildCommand script, causing the error "unknown or unexpected option: --platform".

Solution:
Added the following lines at the top of the script (after imports):

// Filter out EAS Build's unwanted arguments
process.argv = process.argv.slice(0, 2);

This solution strips all command-line arguments passed to the script, keeping only the essential Node.js executable path and script path. Since our prebuild script doesn't require any arguments, this approach safely ignores EAS Build's additional parameters while preserving the script's functionality.

Result:
The script now runs successfully during EAS Build's prebuild phase without being affected by the platform-specific arguments that EAS Build automatically appends.

[ManishSalesgent]

I have tried this but still i get the same error. unknown or unexpected option: --platform
this is my fetch-credentials.js script

#!/usr/bin/env node

import { Buffer } from "buffer";
import fs from "fs";
import fetch from "node-fetch";
import path from "path";
// Filter out EAS Build's unwanted arguments
process.argv = process.argv.slice(0, 2);
async function main() {
if (!process.env.API_ENDPOINT) {
throw new Error("API_ENDPOINT is not defined");
}

console.log("Fetching app configuration from:", process.env.API_ENDPOINT);

try {
const response = await fetch(
${process.env.API_ENDPOINT}/api/store/appconfig
);
const data = await response.json();

const ios = data?.result?.data?.production?.ios || {};
const android = data?.result?.data?.production?.android || {};

// Ensure assets directory exists
const outDir = path.resolve("assets/images");
if (!fs.existsSync(outDir)) fs.mkdirSync(outDir, { recursive: true });

// Use iOS icon for both platforms
let iconPath = "./assets/images/icon.png"; // default
if (ios.icon) {
  try {
    const res = await fetch(ios.icon);
    if (!res.ok)
      throw new Error(`Failed to download icon: ${res.statusText}`);
    const buffer = Buffer.from(await res.arrayBuffer());
    iconPath = path.join(outDir, "icon.png");
    fs.writeFileSync(iconPath, buffer);
    console.log("✅ Icon downloaded for both iOS and Android");
  } catch (error) {
    console.warn("⚠️ Failed to download icon:", error.message);
  }
}

// Write configuration to .env.production
const envContent = `

APP_NAME=${ios.appName || "DefaultApp"}
IOS_BUNDLE_ID=${ios.bundleId || "com.example.default"}
ANDROID_PACKAGE_NAME=${android.bundleId || "com.example.default"}
APP_ICON_IOS_PATH=${iconPath}
APP_ICON_ANDROID_PATH=${iconPath}
APPLE_ID=${ios.appleId || ""}
APPLE_TEAM_ID=${ios.appleTeamId || ""}
ASC_APP_ID=${ios.ascAppId || ""}
SKU=${ios.sku || ""}
LANGUAGE=${ios.language || "en-US"}
`.trim();

fs.writeFileSync(".env.production", envContent);
console.log("✅ Configuration written to .env.production");

// Set environment variables for current process
process.env.APP_ICON_IOS_PATH = iconPath;
process.env.APP_ICON_ANDROID_PATH = iconPath;
process.env.APP_NAME = ios.appName || "DefaultApp";
process.env.IOS_BUNDLE_ID = ios.bundleId || "com.example.default";
process.env.ANDROID_PACKAGE_NAME =
  android.bundleId || "com.example.default";

} catch (error) {
console.error("Failed to fetch app config:", error);

// Fallback environment file
const fallbackEnvContent = `

APP_NAME=DefaultApp
IOS_BUNDLE_ID=com.example.default
ANDROID_PACKAGE_NAME=com.example.default
APP_ICON_IOS_PATH=./assets/images/icon.png
APP_ICON_ANDROID_PATH=./assets/images/icon.png
APPLE_ID=
APPLE_TEAM_ID=
ASC_APP_ID=
SKU=
LANGUAGE=en-US
`.trim();

fs.writeFileSync(".env.production", fallbackEnvContent);
console.log("✅ Fallback configuration written to .env.production");

}
}

main().catch((err) => {
console.error("❌ Failed in fetch-credentials:", err);
process.exit(1);
});

and this is eas.json

{
"cli": {
"version": ">= 12.3.0",
"appVersionSource": "remote"
},
"build": {
"development": {
"developmentClient": true,
"distribution": "internal"
},
"preview": {
"distribution": "internal"
},
"production": {
"autoIncrement": true,
"android": {
"buildType": "apk"
},
"env": {
"API_ENDPOINT": "https://dev.example.com",
"VERSION": "1.0.0"
},
"prebuildCommand": "expo run:node scripts/fetch-credentials.js && expo prebuild"
}
},
"submit": {
"production": {}
}
}