Community Questions

Overview: What changes between Joomla 3.10 and Joomla 4 (brief)

Joomla 4 modernized the CMS: a refreshed administrator interface, updated libraries, stricter PHP practices, and removal of some deprecated APIs. Those changes improve performance and security, but they can break extensions or templates that rely on older Joomla 3 APIs.

Why compatibility warnings appear

• Developers mark compatibility in extension manifests; an “incompatible” flag or missing Joomla 4 declaration is a warning that the extension wasn't tested or updated for Joomla 4.
• Extensions that use removed or deprecated core classes, helpers, or event triggers may fail after the core is upgraded.
• Some extensions labeled “unknown” could still function, but they are untested — only staging tests will confirm behaviour.

Practical example

Example: a custom module that calls Joomla 3-only helper classes could generate fatal errors in Joomla 4. On staging, this will show as PHP errors in logs or a blank page; testing allows you to catch and fix it without affecting production.

Before you start: prepare, document and back up

Preparation reduces risk. A complete audit and reliable backups are the minimum prerequisites before attempting any upgrade.

Document your site

• Note the exact Joomla version (3.10.x), PHP version, database type/version, and hosting details.
• Make an inventory of installed extensions and templates: name, version, vendor, and what they do (critical vs optional).
• Save screenshots of template settings, custom code areas, and critical component configuration pages.

Required backups (database + files) and recommended tools

• Full file backup: webroot files including configuration.php, media/uploads and any custom code folders.
• Full database backup: SQL dump of the site database.
• Recommended options: Akeeba Backup (extension), hosting snapshots, or manual FTP + mysqldump. Store backups off-site or in a different server location.

Practical example: Create an Akeeba archive, download it to local storage, and verify the archive contains both the SQL file and site files. Then restore that archive to staging to confirm it’s usable.

Check server and PHP requirements (verify official docs)

Joomla 4 requires more recent server components than older Joomla versions. Confirm your PHP and database versions and server PHP extensions before upgrading. Exact minimums can change; verify them on the official Joomla documentation before making production changes.

How to check PHP and database versions

• From Joomla admin: System → System Information shows PHP and database details.
• Use phpinfo() in a test file or run CLI commands: php -v and database commands such as mysql --version or mariadb --version on systems that allow CLI access.
• If your host provides a control panel, it often shows and lets you change the PHP version per site.

Practical example: If your site is on PHP 7.2 but Joomla 4 requires a newer PHP, schedule a PHP upgrade on staging first and verify all extensions and templates run under the newer PHP before upgrading the core.

Audit installed extensions, plugins and templates

Make an actionable inventory so you can triage what must be fixed before a live upgrade.

Use Extension Manager to list and export extensions

• Go to Extensions → Manage → Manage. Filter and capture the list (screenshot or CSV if available).
• Record: Extension name, current version, vendor, installed date, and whether it is critical to site operations.

Find extension compatibility information (developer pages, JED)

• Check the Joomla Extensions Directory (JED) and the developer’s website for Joomla 4 compatibility statements and changelogs.
• If compatibility info is missing, mark the extension as Unknown and plan to test it on staging.

Prioritize extensions

• Classify each extension as Critical (payment, login, booking), Recommended (SEO, caching), or Optional (analytics widgets, cosmetic modules).
• Focus effort on ensuring Critical extensions are Joomla 4-ready or have reliable replacements.

Options for incompatible extensions: update, replace, or remove

When an extension is flagged incompatible, you have three main choices: update it if a Joomla 4-ready release exists; replace it with an actively maintained alternative; or remove or disable it if it’s non-essential.

Update

• If the vendor has released a Joomla 4 compatible version, install that update in staging and test thoroughly.
• Follow the vendor’s upgrade notes and changelog; some updates include migration steps for stored data.

Replace

• For abandoned or permanently incompatible extensions, identify equivalent extensions that explicitly support Joomla 4 and have active development.
• Plan how data will move from old to new: export/import tools, CSV, or migration scripts may be needed.

Remove / Disable

• Temporarily disabling optional extensions can let you upgrade the core and restore features later.
• Be cautious: removing an extension may delete its data; check vendor docs and back up data first.

Replacing abandoned extensions: migration approaches

1. Inventory how the extension stores data (own DB tables, uses Joomla core tables, or stores JSON in fields).
2. Export data from the old extension and import into the new one where possible. For complex migrations, a developer or custom script may be required.
3. Keep both systems available on staging until migration is verified; avoid running two extensions that conflict on production without proper testing.

Create a staging copy and test the upgrade

Never run a major core upgrade on production without staging tests. A staging environment lets you reproduce problems and fix them safely.

How to clone the site to a staging environment (host tools or manual)

• Option A — Hosting one-click staging: Many hosts provide a staging feature that clones files and DB automatically; follow host documentation.
• Option B — Manual clone: Copy files via FTP or control panel, export/import the database, adjust configuration.php to point to the new database and URL, and protect staging with a password.
• Restore an Akeeba archive with Akeeba Kickstart to staging for a reliable full-site restore if you have an archive.

Running the Joomla Pre-Update Checker

• Install and run the Pre-Update Checker on the staging copy to get a report of potential issues (extensions, templates, system settings).
• Interpret results carefully: errors must be fixed before attempting a core upgrade; warnings should be triaged and tested.

Step-by-step: performing the upgrade on staging

Follow a clear sequence to minimize interdependent failures. Document each action so you can reproduce it on live.

Recommended sequence

1. Update all installed extensions to their latest Joomla 3.10-compatible releases (where available).
2. Ensure staging PHP meets Joomla 4 minimums; if you must change PHP, do it now and test the site.
3. Run the Pre-Update Checker again and resolve any errors.
4. Make a fresh backup/snapshot of staging.
5. Use the Joomla Update component to move to the latest Joomla 3.10.x if not already on it.
6. Run the Joomla 4 updater in the Joomla Update component or follow the documented update package process.
7. Watch the upgrade process: do not interrupt database migrations or update steps.

CLI and database migration notes

• Some advanced workflows use CLI or Composer for updates. Only use CLI if you are comfortable with the commands and confirm the correct syntax and behavior from official docs first.
• Allow the updater to complete database schema changes and avoid cancelling the operation mid-migration.

Validate the upgraded site and common post-upgrade checks

After a successful upgrade on staging, run a verification checklist to ensure the site behaves as expected.

Key validation items

• Admin login and administrator area functions.
• Frontend pages load and templates render correctly (desktop and mobile views).
• Forms submit successfully and emails are sent (if enabled on staging, or simulated if not).
• E-commerce flows (add-to-cart, checkout, payment gateway test) if applicable.
• Third-party extension functionality, especially critical ones, behaves as expected.
• Check PHP and Joomla logs for warnings or errors and resolve them.

Performing the live site upgrade safely

Only apply the process to production when the staging site is clean and all critical extension issues are resolved or mitigated.

Live upgrade checklist

1. Create a final pre-upgrade backup and host snapshot.
2. Notify stakeholders and schedule a low-traffic maintenance window.
3. Enable maintenance mode on live.
4. Repeat the exact steps you used in staging: update extensions, switch PHP if needed, then run the Joomla core upgrade.
5. Run quick smoke tests: admin login, homepage, contact form, and any checkout flow. If all OK, remove maintenance mode and monitor closely for 24–48 hours.

Rollback triggers and rules

• Decide ahead of time what constitutes a rollback (site inaccessible, checkout broken, admin locked out).
• If rollback is required, restore files and database from the pre-upgrade backup or host snapshot following your backup tool’s documented restore process.

Troubleshooting, rollback and recovery steps

If the site exhibits problems after upgrade, use logs and controlled changes to identify and fix the issue. When necessary, restore the pre-upgrade backup.

Common errors after upgrade and quick fixes

• Fatal PHP errors: check PHP version and enabled PHP extensions. If the error points to a third-party extension, disable it temporarily.
• Broken layout or missing CSS/JS: switch to the default Joomla template (Cassiopeia) to determine if the custom template is the cause.
• Extension API errors: disable the extension via the Extensions Manager or via a database change if admin access is unavailable (document the exact setting change before editing DB).

Rollback example: restoring database and files after a failed live upgrade

1. Put site into maintenance mode to pause user activity.
2. Restore files from the backup archive or host snapshot.
3. Restore the database from the SQL dump or snapshot.
4. Clear Joomla caches and verify admin access and key pages.

When to hire a Joomla developer or extension specialist

Certain situations are best handled by an experienced Joomla professional.

When to get professional help

• If your site uses heavily customized extensions, many template overrides, or critical e-commerce systems that cannot tolerate downtime.
• If you need custom migration scripts to move data from an abandoned extension to a replacement.
• If the upgrade process requires CLI or Composer approaches and you lack command-line experience.

What to ask and expect

• Ask for a migration plan, estimated downtime, rollback procedures, and references for similar work.
• Prepare a briefing document for the developer: site inventory, backups, staging access, error logs, and steps you’ve already taken.

Summary checklist

Use this compact checklist as your upgrade flow:

1. Document current environment (Joomla, PHP, DB, extensions, template).
2. Create full backups (files + DB) and verify a restore on staging.
3. Audit extensions and classify critical vs optional; check compatibility notes.
4. Build a staging copy and lock it from indexing/email sends.
5. Update extensions on staging, switch PHP if needed, run Pre-Update Checker.
6. Upgrade Joomla core on staging and validate all critical functionality.
7. Plan and perform live upgrade copying the tested staging steps; have rollback ready.
8. Monitor live site and logs closely for 24–48 hours after go-live.

Quick actions to take if you see "incompatible" warnings

• Do not click the core update on the live site until staging is clean.
• For each incompatible extension: try to update (preferred) → if not available, replace → if optional, consider disable/remove.
• Contact developers for compatibility timelines if the extension is business-critical.

FAQ

Will my site "blow up" if I click to upgrade from Joomla 3.10 to Joomla 4?

Short answer: it's possible that incompatible extensions or templates could break functionality. That is why you should take backups, clone to staging, test the upgrade, and verify critical features. If staging testing reveals unresolved critical issues, do not run the upgrade on production.

Do I need to update all extensions before upgrading Joomla core?

Update extensions that have Joomla 4-compatible releases first, especially critical ones. For extensions with unknown or no Joomla 4 support, plan to replace, remove, or test them on staging. Never update the live core without first testing extension updates in staging.

How do I check if an extension supports Joomla 4?

Check the Joomla Extensions Directory (JED), the extension developer’s website and changelogs, and use the Pre-Update Checker on a staging copy. If no info is available, mark the extension as "unknown" and test it on staging or contact the vendor.

What server and PHP versions do I need before upgrading?

Server requirements for Joomla 4 are stricter than for Joomla 3.10 and can change between Joomla 4 subversions. Always verify the exact minimum PHP and database versions on the official Joomla documentation before performing the upgrade.

Can Joomla core automatically update third-party extensions?

No — the Joomla core updater handles core updates. Third-party extensions normally provide their own update packages; some extension updates appear in Joomla’s Extension Manager if the developer has configured update servers. Verify how each extension is updated by reading vendor documentation.

What if an extension I need is abandoned?

Search for actively maintained replacements and plan a data migration. If there is no suitable replacement, hire a developer to port or rewrite the extension. Back up and test migration steps carefully on staging before performing them in production.

How can I rollback if something goes wrong during the live upgrade?

Rollback options: restore from your full pre-upgrade backup (Akeeba archive or manual backup) or restore a hosting snapshot. Confirm the restore procedure and timing with your backup tool or host before you upgrade, and be aware that any content created after the backup may be lost unless exported and re-imported.

Conclusion

Upgrading from Joomla 3.10 to Joomla 4 is a manageable but sometimes involved process. The keys to success are careful inventory and documentation, reliable backups and a restore test, a staging environment that mirrors production, and a disciplined approach to handling incompatible extensions (update, replace, or disable). When in doubt or when the site is business-critical, engage an experienced Joomla developer.

Verify all technical details (version numbers, CLI commands, backup/restore steps) against the official Joomla documentation and any vendor documentation before changing a production site.