Laravel 12 Breaking Changes You Must Fix After Upgrade

Why Laravel 12 Breaking Changes Matter

Upgrading to Laravel 12 improves performance, stability, and long-term support—but it also introduces breaking changes that can silently break production applications if ignored.

This blog highlights the most common breaking changes developers face after upgrading and explains what you must fix immediately.

These are issues developers search for daily after a Laravel 12 upgrade.

1️⃣ PHP Version Requirement Changes

Laravel 12 requires a newer PHP version than Laravel 10.

Symptoms

• Application fails to boot
• Composer install/update errors
• CI/CD pipeline failures

What to Fix

• Upgrade PHP locally and on production servers
• Update PHP version in Docker, CI, and hosting configs
• Verify extensions compatibility

2️⃣ Strict Type Enforcement Errors

Laravel 12 introduces stricter typing across core components.

Symptoms

• Return type mismatch errors
• Fatal errors in overridden methods
• Errors in custom services or repositories

What to Fix

• Ensure child classes match parent method signatures
• Fix return types in models, policies, and services
• Review custom overrides carefully

3️⃣ Middleware and Bootstrap Changes

Laravel continues moving logic into bootstrap/app.php.

Symptoms

• Middleware not executing
• Auth or session issues
• CSRF or API middleware failures

What to Fix

• Re-check middleware registration
• Avoid relying on removed default middleware
• Explicitly register required middleware

4️⃣ Removed or Changed Configuration Defaults

Some configuration values are removed or simplified in Laravel 12.

Symptoms

• Features behave unexpectedly
• Missing config values
• Environment-specific issues

What to Fix

• Compare your config/ files with a fresh Laravel 12 install
• Restore only required custom configurations
• Remove unused or deprecated config entries

5️⃣ Composer Dependency Breakage

Many third-party packages may not fully support Laravel 12 yet.

Symptoms

• Composer dependency conflicts
• Runtime errors from packages
• Missing service providers

What to Fix

• Update all dependencies
• Replace unsupported packages
• Remove abandoned libraries

Tip: Upgrade Laravel first, then add packages back one by one.

6️⃣ Queue and Job Execution Issues

Queue behavior may change due to internal improvements.

Symptoms

• Jobs failing silently
• Serialization issues
• Workers not processing jobs

What to Fix

• Restart queue workers after upgrade
• Review custom job classes
• Test queue execution manually

7️⃣ Test Failures After Upgrade

Even working apps often have failing tests after upgrading.

Symptoms

• PHPUnit failures
• Deprecated assertions
• Type-related test errors

What to Fix

• Upgrade PHPUnit
• Update deprecated test methods
• Fix strict typing in test helpers

Post-Upgrade Must-Do Checklist

After upgrading to Laravel 12:

• Clear all application caches
• Rebuild config and route caches
• Restart queue workers and schedulers
• Verify authentication and authorization
• Test APIs, emails, and file uploads
• Monitor logs for at least 24 hours

Final Thoughts

Laravel 12 is a strong upgrade—but only if breaking changes are handled properly.
Most issues come from strict typing, removed defaults, and outdated packages.

Fixing these early ensures:

• Stable production deployments
• Fewer runtime surprises
• Long-term maintainability