Jimmy Wong

The Evolution of Symfony: From 1.4 to 6.4 ​

Symfony Conductor

Symfony has been a cornerstone of modern PHP development for nearly two decades. What started as a framework to help developers build robust web applications has transformed into a powerful ecosystem with cutting-edge tools and practices. In this post, we’ll take a journey through the major milestones of Symfony from version 1.4 to the current 6.4 LTS release.

Symfony 1.4 (2009) – The End of an Era ​

Released in November 2009, Symfony 1.4 was the final release in the 1.x series and marked the end of Symfony’s “monolithic” architecture. At this point, Symfony was already popular for its conventions, scaffolding features, and admin generators. However, it was still tightly coupled and lacked modern PHP features introduced in PHP 5.3 and beyond.

Highlights:

  • Based on the full-stack approach.
  • Final stable version before Symfony 2’s complete rewrite.
  • Heavily used in legacy enterprise apps.

Symfony 2.x (2011–2015) – A New Beginning ​

Symfony 2.0 was released in July 2011. It was a total rewrite that embraced decoupling, dependency injection, and modularity. Symfony 2 introduced the concept of reusable Bundles, paving the way for component-driven development.

Key milestones: ​

  • 2.0 (2011): Full rewrite with a strong focus on components and service containers.
  • 2.3 (2013): First Long-Term Support (LTS) version.
  • 2.7 (2015): Final LTS of the 2.x line.

This era solidified Symfony as a modern framework and laid the foundation for many other projects, including Laravel, which adopted several Symfony components.

Symfony 3.x (2015–2017) – The Maturation Phase ​

Symfony 3.0 arrived in November 2015. It was more of a polish and refine release than a revolutionary one. The team focused on backward compatibility, deprecations, and cleaning up technical debt.

Highlights:

  • Continued use of components and bundles.
  • Stronger emphasis on DX (Developer Experience).
  • 3.4 (2017): LTS version, used in many enterprise-grade applications.

Symfony Flex, although not yet released, began to influence the conversation around simplifying Symfony projects.

Symfony 4.x (2017–2020) – The Flex Revolution ​

Symfony 4.0, released in November 2017, was a major shift in how Symfony applications were built. With the introduction of Symfony Flex, the framework embraced a micro-kernel architecture and offered a lightweight skeleton with only essential dependencies.

Key innovations: ​

  • Symfony Flex for automated dependency management and recipes.
  • Emphasis on smaller, modular apps.
  • 4.4 (2019): LTS version, widely adopted.

This change greatly improved the onboarding experience and reduced boilerplate code, making Symfony more accessible and modern.

Symfony 5.x (2019–2022) – Streamlining & Performance ​

Released in November 2019, Symfony 5 built upon the architectural clarity of version 4 and continued the framework's focus on performance, developer productivity, and modern PHP features like typed properties.

Major additions: ​

  • Improved Messenger component for asynchronous tasks and queues.
  • Enhanced HTTP Client, Mailer, and Notifier components.
  • Better testing tools with Panther and BrowserKit.

Symfony 5 maintained a high release cadence and served as a bridge between modernization and long-term stability.

Symfony 6.x (2021–Present) – Embracing Modern PHP ​

Symfony 6.0 debuted in November 2021, requiring PHP 8.0+. It stripped deprecated features and focused on clean, modern APIs. With this version, Symfony fully committed to the typed, strict paradigm that modern PHP offers.

Symfony 6.4 (November 2023) – Current LTS ​

  • Final LTS of the 6.x line.
  • Requires PHP 8.1 or higher.
  • Integrates new components like Clock, Scheduler, and improvements to UX packages.
  • Focuses on sustainability, stability, and performance.

6.4 is widely used in production and will be maintained until November 2026 (bug fixes) and November 2027 (security fixes).

Looking Ahead: Symfony 7 and Beyond ​

Symfony 7.0, planned for November 2024, will drop support for deprecated 6.4 features and continue Symfony’s mission of leading modern PHP development. The focus will likely include even deeper PHP 8.2/8.3 features, better async support, and enhanced DX.

Conclusion ​

From its early monolithic roots in Symfony 1.4 to the powerful, component-based ecosystem in 6.4, Symfony has consistently adapted to the evolving PHP landscape. It has influenced countless other frameworks, powered major platforms, and helped developers build everything from small websites to enterprise-scale applications.

Whether you're maintaining a legacy 1.4 app or building with the latest 6.4 LTS, the journey of Symfony reflects the progress of PHP itself—a transformation from procedural scripts to modern, typed, object-oriented architecture.

Copyright © 2025 Jimmy Wong