Laravel PackageManifest.php: Undefined index: name

Problem Overview

The error Undefined index: name in PackageManifest.php typically occurs when there's a compatibility issue between your Laravel framework version and Composer. This error appears when Laravel attempts to parse the installed.json file generated by Composer but encounters an unexpected structure.

WARNING

This error most commonly affects older Laravel versions (5.5-6.x) when used with Composer v2, which changed the structure of the installed.json file.

Root Cause

Composer v2 introduced a breaking change to the structure of the installed.json file located in vendor/composer/. While Composer v1 created a flat array of packages, Composer v2 nests packages under a packages key. Older Laravel versions didn't account for this structural difference, causing the "Undefined index: name" error when trying to access package information.

Recommended Solutions

1. Update Laravel Framework (Recommended)

The most robust solution is to update your Laravel framework to a version that officially supports Composer v2:

// composer.json
{
  "require": {
    "laravel/framework": "5.5.49 || ^5.6.40 || ^5.7.29 || ^6.20.0 || ^7.0 || ^8.0 || ^9.0 || ^10.0 || ^11.0"
  }
}

Update specific version

composer require laravel/framework:5.5.49

Update to latest compatible

composer update laravel/framework

Minimum Compatible Versions

• Laravel 5.5: 5.5.49+
• Laravel 5.6: 5.6.40+
• Laravel 5.7: 5.7.29+
• Laravel 5.8: 5.8.38+
• Laravel 6.x: 6.20.0+

2. Clean Install Approach

If updating isn't immediately possible, try a clean install:

# Remove existing dependencies
rm -rf vendor/ composer.lock

# Reinstall with current Composer version
composer install

3. Temporary Manual Fix

For immediate resolution without updates, modify the PackageManifest.php file:

// vendor/laravel/framework/src/Illuminate/Foundation/PackageManifest.php

if ($this->files->exists($path = $this->vendorPath.'/composer/installed.json')) {
    // Replace this line:
    // $packages = json_decode($this->files->get($path), true);
    
    // With these lines:
    $installed = json_decode($this->files->get($path), true);
    $packages = $installed['packages'] ?? $installed;
}

DANGER

Manual edits to vendor files are temporary and will be overwritten by future Composer operations. Use this only as a short-term solution.

4. Downgrade Composer (Last Resort)

If you cannot update Laravel, consider downgrading Composer:

# Downgrade to Composer v1
composer self-update --1

# Or install specific v1 version
composer self-update 1.10.20

WARNING

Composer v1 is no longer maintained and may have security vulnerabilities. Use this option only if absolutely necessary.

Best Practices for Deployment

1. Avoid composer update in production: Use composer install with a committed composer.lock file for predictable deployments
2. Test compatibility locally: Always test Composer version changes in a development environment first
3. Keep dependencies updated: Regularly update your Laravel framework to receive security patches and compatibility improvements

Version Compatibility Reference

Laravel Version	Minimum Compatible	Composer v2 Support
5.5	5.5.49	✓
5.6	5.6.40	✓
5.7	5.7.29	✓
5.8	5.8.38	✓
6.x	6.20.0	✓
7.x+	All versions	✓

Conclusion

The "Undefined index: name" error is a compatibility issue that arises when using older Laravel versions with Composer v2. The optimal solution is to update your Laravel framework to a compatible version. If immediate updating isn't feasible, the temporary fixes and workarounds provided can help resolve the issue while you plan for a proper upgrade.

Remember to always test compatibility changes in a development environment before deploying to production, and maintain regular updates to your dependencies to prevent similar issues in the future.