How to Run Old Laravel Apps With a Different PHP Version

Overview

• Learn practical solutions for running old Laravel apps with different PHP versions.
• Explore tools to switch PHP, tackle composer errors, and manage multiple environments.
• Get simple guidance for keeping legacy Laravel projects stable and compatible.

Maintaining legacy Laravel applications can be challenging, especially when your project relies on older PHP versions while your system is up-to-date.

Attempting to run outdated apps on modern environments often results in composer errors and compatibility issues. However, developers don’t need to rewrite or upgrade the entire application right away.

By leveraging techniques like multiple PHP installations, Docker containers, or PHP-FPM pools, you can effortlessly run and maintain older Laravel projects alongside new ones, ensuring stability and seamless development.

Ensuring your Laravel application runs smoothly depends heavily on matching it with the appropriate PHP version.

Each Laravel release is designed to leverage specific features and security enhancements introduced in corresponding PHP versions.

Using a mismatch (for example, trying to run Laravel 5.8 on PHP 8.0) can result in serious compatibility problems, including syntax errors, deprecation warnings, and even failed installations.

Here’s a breakdown of how Laravel versions align with supported PHP versions:

Maintaining older Laravel applications that depend on specific, possibly outdated PHP versions is entirely feasible. Several flexible approaches exist to ensure compatibility and stability, allowing developers to run legacy systems without compromising performance or security.

1. Install Multiple PHP Versions on the Same Machine

Installing several PHP versions side-by-side allows you to support both modern and legacy Laravel applications on a single system. 

For example, on Ubuntu, you can use tools like apt to install specific PHP packages and update-alternatives to easily switch between versions whenever your workflow demands it. 

Ubuntu example:

sudo apt install php7.4 php7.4-mysql php7.4-xml php7.4-mbstring

sudo update-alternatives –config php

This flexibility ensures smooth transitions and compatibility across different project requirements, minimizing conflicts and streamlining development without the need for separate environments.

2. Local Development Tools That Support PHP Switching

Modern PHP development tools like Laravel Valet for macOS or similar solutions on other platforms make it easy to switch PHP versions instantly for local projects. 

By running simple commands such as valet use 7.4, developers can adjust their environment to match each Laravel app’s requirements. 

This seamless PHP switching avoids compatibility headaches and accelerates testing, making it ideal for those working with projects targeting different PHP releases.

3. Docker-Based Setup (Recommended for Teams)

Docker lets you create isolated containers with the exact PHP version and dependencies needed for any Laravel app. 

This approach is especially useful for teams, ensuring consistency across different machines and environments. By defining your stack in a Dockerfile, setup becomes repeatable and error-free. 

Developers can easily share and run legacy projects, eliminating “it works on my machine” issues and streamlining both collaboration and deployment.

4. Virtual Hosts With PHP-FPM Pools

On production servers, configuring virtual hosts to use separate PHP-FPM pools allows each website to run with its own dedicated PHP version. 

This setup is ideal for hosting multiple Laravel projects with differing requirements on a single server. Administrators can fine-tune performance and compatibility for each site, ensuring legacy applications stay operational without affecting newer ones. 

It’s a scalable, efficient solution for businesses managing diverse web applications.

Running legacy Laravel projects doesn’t have to disrupt your latest development environment.

With methods such as installing multiple PHP versions, utilizing Docker, or creating separate PHP-FPM pools, developers can easily switch between old and new Laravel applications.

These solutions minimize risk, reduce technical debt, and accelerate project delivery. Instead of rushing major upgrades, embrace these proven strategies to maintain reliability, compatibility, and productivity across all your Laravel projects, regardless of the PHP version they require.