Upgrading PHP 5.6 or older PHP 8 applications to supported PHP versions

A PHP upgrade needs a delivery plan, not just a new version

A business planning a PHP upgrade needs to know what will change, what compatibility work will cost and how day-to-day customer operations will be protected. Moving from PHP 5.6 may require dependency replacements and framework upgrades. An older PHP 8 application may need less work, but its version number alone cannot determine the estimate.

What determines scope and cost

At GiSoft, we start by examining the application’s environment, PHP extensions, Composer packages and integrations. A maintained package may need an update, an abandoned one a replacement, and an unused one may be removable after checking dependencies. Each involves different work and verification.

Test coverage, data quality, hosting constraints and acceptable downtime also shape the plan. The aim is an agreed scope and sequence, not a promise that every migration will be equally straightforward.

What needs protection

Before changes begin, the foundations are a reproducible environment, backups with tested restoration and a repeatable deployment. With the process owner, we identify critical workflows: for example, login, order acceptance, payment or content publication. Regression tests check that required behaviour is preserved.

Not everything needs testing before the first step, but gaps and accepted risks need to be understood. Testing and analysis tools must fit their environment; modern tools cannot simply be assumed to run inside a PHP 5.6 application.

Preparing the move and recovery

The migration path follows framework, package and extension compatibility. We divide work into verifiable stages, although some dependencies must change together. An adapter can separate an integration, such as document generation or payment processing, where that helps replacement. It does not itself fix an incompatible package.

Before release, we verify the application in production-like conditions, including scheduled jobs and background processes. Acceptance criteria, monitoring and recovery procedures are agreed in advance. Returning to the old code may not be enough if data or message formats have changed.

A supported PHP release is one outcome. A clear understanding of dependencies, useful tests and a repeatable route to the next upgrade matter too. They provide a basis for easier maintenance, not a guarantee against future problems.

Engineering details are covered in the companion article “PHP migration in Symfony and Laravel: a technical guide”.