CodeIgniter upgrade
CodeIgniter 2 and 3 applications can be modernised. The framework itself has largely been left behind.
CodeIgniter was a favourite for fast, lightweight PHP applications, and many businesses still run systems built on versions 2 and 3. The problem is that those versions are no longer being developed, the project's focus is CodeIgniter 4, and the PHP versions they were written for are long out of support.
I help you decide what to do, and do it without breaking what the application already does.
Book a free conversationLegacy System Assessment, from £2,500
Where things stand
Checked October 2026. Confirm at codeigniter.com.
| Version | Status | What it means |
|---|---|---|
| CodeIgniter 1 and 2 | Long unmaintained | Written for PHP 5-era servers. No security fixes |
| CodeIgniter 3 | No longer being developed. The latest release is 3.1.13 | No new releases, and modern PHP isn't supported out of the box. As far as I know, an unmodified 3.1.13 supports PHP up to 8.1, and PHP 8.1 is itself end of life. Running it on newer PHP needs patches |
| CodeIgniter 4 | Current, actively maintained | A different framework. Not backward compatible with version 3, so moving to it is a port, not an upgrade |
The upshot: a CodeIgniter 3 application on a supported PHP version is almost always running patched code, and a patched, unmaintained framework is a stopgap. PHP end-of-life dates
Your options
| Option | What it involves | Best when | Watch out for |
|---|---|---|---|
| Patch CodeIgniter 3 to run on newer PHP | Fix incompatibilities in the framework and your code so it runs on PHP 8.x | You need time, or the application is small and stable | You're maintaining an abandoned framework yourself. It's a bridge, not a destination |
| Migrate to CodeIgniter 4 | Port the application to the current CodeIgniter | You like the framework and the application is standard CodeIgniter 3 structure | It's a real port: namespaces, routing, models, libraries and views change |
| Move to another framework (for example Laravel), in stages | Replace the application piece by piece, or rebuild module by module | The business wants a larger ecosystem, or you already use that framework elsewhere | More work. Needs careful planning. Laravel upgrades |
| Replace the system | Move to a packaged product | Your needs are no longer special | Migration and fit |
| Leave it | Keep running, with monitoring | Stable, low-risk, rarely changed, and not on a deadline | Risk grows. Not for anything handling personal or payment data |
Which is right depends on evidence: how big the application is, how standard its structure is, how many third-party libraries it uses, and what the business needs next. Rewrite vs refactor vs upgrade
How I approach it
1. Assess
I map the framework version, PHP version, database, third-party libraries, custom "core" changes, and how far the application departs from standard structure. AI-assisted analysis speeds this up greatly, and every finding is checked on the real system. How I use AI
2. Build a safety net
Most CodeIgniter 3 applications have thin or no tests. Before changing anything big, I write tests that capture what the system does today, so a change that alters behaviour is caught.
3. Choose the route, with costs
You get the options above with costs and risks for your system, so you decide with evidence.
4. Make the move in steps
Whether it's patching, porting to CodeIgniter 4, or replacing modules gradually, each step is small, tested and reversible, with the application working at every stage.
5. Test, roll out, hand over
Testing on a copy, a planned rollout with rollback, and documentation of what changed. PHP upgrades
What typically causes trouble
- PHP version incompatibilities. Removed functions, changed behaviour and deprecations such as dynamic properties in newer PHP, which old framework code relies on heavily
- Modified framework "core", where someone changed the framework files directly
- Third-party libraries and "sparks" that are abandoned or incompatible
- The old database layer. Active Record style code and raw queries throughout
- Mixed responsibilities. Controllers doing everything, with business logic buried in views
- No namespaces and global state, which make safe change difficult
- Hard-coded paths, URLs and server assumptions
None of these is exotic. They're predictable once mapped.
What it costs
Fixed price, after assessment. I can't quote a migration for an application I haven't seen.
- Free conversation
- Legacy System Assessment, from £2,500: framework, libraries, PHP, database, server and risks mapped, with options costed
- Fixed-price quote for the route you choose. No obligation to continue
What affects cost: size, how standard the structure is, library count, test coverage and integrations. Direct day rate is £950; urgent work from £1,300 per day. Pricing
For agencies
A client on CodeIgniter 3 and a host about to drop their PHP version? I can take it on white-label, or direct with you as referrer. Agency terms
Frequently asked questions
Is CodeIgniter 3 still supported?
It's no longer being developed. The project's focus is CodeIgniter 4. Running version 3 on modern PHP typically means patching it yourself.
Can I just move to CodeIgniter 4?
Yes, but it's a port, not an upgrade. CodeIgniter 4 isn't backward compatible, so the application's structure, routing, models and views have to be adapted. How much work depends on how standard your application is.
Should I stay with CodeIgniter?
Not necessarily. It's a reasonable choice if you like it, but a move to a larger ecosystem can also make sense. I'll tell you honestly which fits your system.
Will my host drop my PHP version?
Possibly. If your host has given you a date, tell me. Host ending PHP support
Do I need to rewrite from scratch?
Rarely. A staged port or replacement is almost always safer. Rewrite vs refactor vs upgrade
How long will it take?
It depends on the size and structure of the application. I'll give you a timeline with the fixed-price quote.
Tell me what you've inherited.
Tell me your CodeIgniter and PHP versions and what's worrying you. I'll tell you honestly what the options are.
Book a free conversationLegacy System Assessment, from £2,500