How to Check Extension Compatibility Before Upgrading Joomla

Build an inventory of the extensions the site actually depends on

Go to System → Manage → Extensions and review installed third-party extensions. Include components, modules, plugins, packages, libraries, templates, and other extension types.

For each important extension, record:

• installed version;
• vendor/developer;
• enabled state;
• purpose on the site;
• whether it stores business-critical data;
• whether it has custom overrides or integrations;
• whether it is still actively maintained.

This inventory is especially important on older Joomla sites where unused extensions may have remained installed through several upgrade cycles.

Check the Joomla Pre-Update Check for the target version

Go to System → Update → Joomla and review the extension compatibility section of the Pre-Update Check. Joomla can report compatibility when the extension's update metadata supplies the necessary target-platform information.

Use the result as evidence, not as an absolute guarantee:

• a compatible status is encouraging, but it does not test every feature of the extension;
• an update-required status means you should follow the vendor's documented update sequence before the Joomla upgrade;
• missing compatibility information means Joomla cannot verify the extension from its update metadata;
• a potential upgrade issue should be investigated before you proceed.

Verify compatibility with the extension developer

Check the developer's current release notes, download page, documentation, or support information for an explicit statement about the Joomla version you plan to install. Also confirm the supported PHP versions.

Do not rely only on a marketplace listing that says an extension supports “Joomla 5/6” without confirming that your exact installed extension version supports the target release. You may need to update the extension before upgrading Joomla.

For a package with multiple plugins or modules, verify the package as a whole. One outdated child plugin can cause a fatal error even when the main component works.

Check the required upgrade order

Major Joomla migrations sometimes require an extension to be upgraded in a specific order. A vendor may require you to:

1. install the newest extension release that still supports your current Joomla version;
2. run the extension's database migration or maintenance step;
3. disable or remove an obsolete plugin;
4. upgrade Joomla;
5. install a post-upgrade extension release intended for the new Joomla version.

Skipping an intermediate release can cause database schema mismatches, missing files, or installer-script failures even when the newest extension version itself supports the target Joomla release.

Test the extension on a staging copy with the target environment

Create a staging copy from a current production backup and perform the same upgrade sequence you plan to use on the live site. Test with the PHP version, database version, Joomla version, and extension versions intended for production.

After the Joomla upgrade, test the extension's actual workflows rather than merely checking whether its Administrator page opens. Depending on the extension, that can include:

• frontend forms and submissions;
• login, registration, and access control;
• payments and callbacks;
• scheduled tasks and cron jobs;
• email and notification delivery;
• file uploads and media processing;
• API calls and webhooks;
• template layouts and overrides;
• data editing, saving, searching, and reporting.

Review PHP, Joomla, and browser-console errors while you test. Deprecated-code warnings on the old site can be useful clues that an extension is relying on APIs removed in the target Joomla version.

Make a clear keep, update, replace, or remove decision

By the end of the compatibility review, every important extension should have one of four outcomes:

• Keep — the current version is verified for the target environment.
• Update — install the vendor's compatible version through the documented migration path.
• Replace — migrate to another extension because the current product does not support the target Joomla version.
• Remove — safely uninstall an extension the site no longer needs after preserving any required data.

Once the inventory is resolved, rerun Joomla's Pre-Update Check, create a fresh full backup, and repeat the staging upgrade from a clean recovery point. Production should be the final repetition of a process you have already proven, not the first place you discover whether an extension is compatible.