How to Upgrade PHP: Guide to Planning and Executing PHP Upgrades

What's the best way to upgrade PHP?

If you're asking yourself this question, you're not alone. After all, PHP upgrades unlock improved security, better performance, and new features. However, they also represent a challenge for any team, particularly those battling tight time or resource constraints. Plus, with PHP versions only community supported for four years, teams need to upgrade PHP versions frequently – or face the reality of deploying unsupported EOL versions.

In this blog, I look at some of the benefits and challenges involved with PHP upgrades. I then walk through the basics of how to upgrade PHP, providing tips and expert advice along the way to simplify your next project.

Why Upgrade PHP?

Working to upgrade PHP brings key benefits like stronger security, faster performance, and access to modern language features. Staying current helps reduce technical debt, improve maintainability, and keep applications scalable and supported for the long term. 

Here are a few examples:

• Improved Performance
• Better Security
• More Community Support

Upgrading PHP Improves Performance

Upgrading to the latest PHP version gives you access to significant jumps in web application performance. These performance gains can translate into faster response times for users and improved service levels. In addition, application performance gains can sometimes make significant hardware consolidation possible, which can result in thousands of dollars of monthly savings.

PHP Upgrades Lead to Better Security

As with all languages, new versions of PHP bring upgrades to PHP security. New CVEs are found over time, and defenses to these are incorporated into updates. Failure to maintain a current PHP version means missing out on defenses against new CVEs and PHP vulnerabilities as they are uncovered.

This isn't for PHP only, but also related libraries. The libraries and tools we use in the PHP environment are also tied to PHP versions and generally require a supported version of PHP to be updated. Sticking with an outdated version of PHP can expose your system to numerous security vulnerabilities beyond those expressly in PHP itself.

Upgrade PHP for More Active Community Support

This aspect ties into what we just discussed about PHP's interactions with different libraries and tools. Each library and tool will only maintain compatibility with select versions of PHP. An example of a common package is the Symfony Filesystem. 

The current version (7.1.2) only supports PHP 8.2 and above. While PHP 8.1 will continue receiving updates through the end of 2025, some package maintainers are only focusing on PHP versions in active support. Additionally, new and exciting tools and updates are usually only designed with the current and community supported versions of PHP in mind.

Considerations for PHP Upgrades

Typically, the biggest challenges people face when planning to upgrade PHP relate to justification, planning, and cost. It’s not unusual for PHP applications to have several million lines of code, and the scope of manually upgrading PHP versions to a new release can be daunting, especially when it comes to scheduling updates around an already busy schedule. 

Developer Time and Skill Set

Upgrading PHP applications simply takes a lot of time. It requires developers to comb through the application and replace or alter working code to make it compatible with the upgraded PHP version. This can be more complicated as it sounds, as PHP upgrades can open all sorts of closets full of skeletons. Those dangerous parts of the code that are very complex? Changing them can lead to a number of side effects.

For larger applications, including enterprise web applications, you will require skilled PHP developers to understand exactly what is happening before a change is made. If your developers are unfamiliar with the code or PHP, you may experience extreme unintended consequences. This includes increasingly troublesome time constraints due to poorly documented code.

Web Application Downtime

As with any update, major PHP upgrades will require a period of system downtime. This can be avoided through the use of multiple web servers behind a load balancer. Your amount of downtime will vary depending on how your system is set up.

Preparing for Potential Problems After Upgrading PHP

Changing code can always lead to the introduction of new bugs. Some changes to prepare for with a PHP upgrade might simply be a direct replacement of a deprecated function, while others are more complex.

Adjusting your code base for a PHP version upgrade can require changes that are not limited to a certain portion of the code base. While these risks can be mitigated with appropriate testing and time, therein lies the issue - time. While your developers are preparing for the PHP upgrade, they are not working on other known issues or developing new features. Thus project management needs to prepare expectations for development time dedicated to neither features nor issue resolutions. 

How to Upgrade PHP

Each version of PHP is only under active development for two years before it drops to only security fixes for an additional two years. Given this fast lifecycle, teams are tasked with upgrading PHP versions more often than ever before. To help make the transition as smooth as possible, we've compiled this list of tips for how to upgrade PHP versions.

1. Plan Extensively Before Starting to Upgrade PHP

There are two things I always stress when it comes to planning a PHP upgrade:

• Schedule Extensive Tests - Testing goes alongside migration success. Be sure to fully test your application using a variety of PHP testing techniques.
• Migrate Code in Small Sprints - Break your migration into small sprints for better results.

To help make your migration planning a success, we have assembled a free white paper. It details the best practices teams need to consider when planning and executing PHP upgrades and migrations.

Download Your Free Copy

2. Complete Application Testing in a Staging Environment

Is testing a necessary step to upgrade PHP? Yes, it is extremely necessary. Any change to your PHP application should always go through rigorous PHP testing, including but not limited to unit tests, integration testing, and end-to-end testing. A strong QA and testing environment is necessary for trouble-free deployments.

Testing becomes more feasible if you do it as you make changes. Waiting to run all your tests until you are done with your code migration will make it much more difficult and time-consuming to pinpoint issues and their causes. I recommend making one change, and then testing it. Repeat this cycle until the upgrade is complete.

3. Upgrade PHP Packages and Libraries

A PHP upgrade to a more current version may require updates to many of the packages and libraries your applications uses. Some might simply not work with the newer version, as they are coded to only work for specific versions of PHP.

Planning ahead is essential as you might run into instances where a package you are using is not supported anymore and cannot be upgraded to a newer version. Proper planning will identify the situations where replacement of the library will be required.

Upgrade PHP Versions Gradually

If the application being upgraded is many versions behind, a common and safe technique is to do a series of smaller jumps. Moving from PHP 5.6 to PHP 8.3 all at once would be a huge change, and the larger the change, the more opportunities there are for both bugs and problems to arise.

Gradual upgrading will also give you better control over time and cost. The complexity and time commitment for each upgrade is smaller, and the opportunity for disruptions to occur is lessened with smaller changes.

How to Upgrade PHP: FAQ

Does PHP Need to be Upgraded?

Yes, PHP needs to be upgraded to remain secure, compliant, and performant. PHP versions have a lifecycle of four years, with two years of active community support followed by two years of security-only support. The lifespan of PHP versions can be extended through third-party long term support, such as PHP LTS from Zend.

Is It Safe to Upgrade PHP?

Yes, it is safe and strongly recommended to upgrade PHP.

In fact, it is more unsafe to remain on out-of-date or unsupported PHP versions. The best way to keep applications secure is to upgrade PHP versions to the most current PHP version available.

What Is the Most Current PHP Version Available?

As of November 2025, the most current PHP version is PHP 8.5.

Final Thoughts

There is no one-size-fits-all answer for the best way to plan and execute your next PHP upgrade, as exact requirements and steps will vary depending on the needs of your application, your developer team's skill sets, and many other factors. 

One solution is to partner with a team of PHP upgrade experts, such as Zend. We offer a full suite of professional services designed to guide you through how to upgrade PHP versions and offer consultation services and ongoing support throughout your migration process. Our experienced professionals work with your cadences, processes, tools, and teams to ensure no detail is missed, help you consolidate infrastructure, and much more.

Additional Resources

• 101 Guide - PHP Security
• Webinar - Modernizing Legacy Web Apps
• Webinar - Are CMS Ecosystems Keeping Pace With PHP?
• White Paper - Planning Your Next PHP Migration
• Blog - PHP 8.1 Upgrade Plans: How to Stay Ahead of EOL
• Blog - Enterprise Application Modernization: Costs to Watch
• Blog - How to Migrate Zend Server to ZendPHP
• Blog - PHP Migrations: When Is Migrating PHP Versions the Right Choice?
• Blog - PHP 8.5: New Features and Deprecations to Know