If you have already dealt with upgrades, you will probably have read and heard that upgrades should never be carried out on a live instance. There is a reason for this: any upgrade or update can go wrong, and not all complications that arise are foreseeable. To be on the safe side, first create a copy of the existing instance on which the upgrade can be performed. It is also advisable to have a backup ready in case structures are damaged during the upgrade and need to be restored. Creating a copy or backup of a TYPO3 instance requires copying all files (via FTP, SCP, rsync or another method) and exporting the database to an SQL file. A content freeze should also be maintained during the entire upgrade process so that content does not have to be entered twice (before and after the upgrade). All other steps described can also be found on the official TYPO3 website.
 

System requirements

Before the actual upgrade begins, you must also check whether the system requirements for the new version are met. It is advisable to use a PHP version that is as up-to-date as possible and compatible with the desired TYPO3 version. For TYPO3 12 PHP 8.1 a minimum requirement.

Update extensions

Before working with the copy, you should check whether the copy works in the same way as the live instance. In the course of this, the extensions should also be checked for deprecations by the Deprecations-Log in the Install Tool. This should run for a few days. Alternatively or additionally, the extension scan should be used. The deprecations should be resolved before the upgrade.

Extensions that are no longer required do not need to be updated and can be deleted directly to reduce the effort involved. This is because updating extensions is often the more time-consuming part of an upgrade compared to the actual TYPO3 core update.

It can happen that extensions are compatible with the desired TYPO3 version, but not with the version used. PHP-Version of the new TYPO3 version. In this case, an older PHP version may have to be used, or the use of such extensions may have to be abandoned, as they will become obsolete sooner or later anyway and alternatives will have to be found. Furthermore, there may be extensions that are displayed as incompatible but still work on the new TYPO3 instance. Here is somethingTesten required. Many extensions can simply be updated to the latest version and continue to be used after the instance has been upgraded. Sometimes, however, the latest version is not available for the old TYPO3 instance. In this case, it may be worth updating the extension to the highest possible version and bringing it up to the latest version after the upgrade.

Some extensions must be deactivated before the upgrade and will be updated after the upgrade. Individual extensions may need to be specially adapted to the new version. This could mean the greatest effort, so it may make sense to use other solutions in the future.

Check reference index

The global reference index manages links between content elements and files. This index can be checked and updated in two ways: either via the command line (CLI) or via the DB check (system modules). As the process can take a lot of time, especially for large websites with many pages and files, and does not need to be carried out regularly, the method via the command line is recommended. The DB check is an alternative, especially for small websites with few subpages and files.

Changelog check

This step is optional, but it is advantageous to prepare an upgrade carefully. Each changelog of a version contains items such as Breaking Changes, Important, Features and Deprecations. It is recommended to at least look at the Breaking Changes and the points under Important. The changelogs can be read in various ways: in theExtension Scanner of the upgrade module in the system modules or online. On the official TYPO3 website you will also find the changelog for TYPO3 12. The Extension Scanner offers the advantage that you can filter by tags and Changelogs like a to-do list can be processed.

Convert global extensions

In earlier versions of TYPO3 Global extensions is an easy way to share extensions between multiple TYPO3 instances. Nowadays it is recommended to share extensions via the Composer to install and maintain. Therefore, with TYPO3 v12 the Support for global extensions removed,they must be in local extensions can be converted.

To convert a global extension into a local one, you have to go to the Backend-Modul Extensions (under Admin Tools) to uninstall the global extension. Furthermore, the files of the extension must be deleted from typo3/ext/, including the directory of the extension itself. The extension must then be reinstalled from the TYPO3 extension repository, which will place it in typo3conf/ext/.

All necessary steps that have to be carried out after the TYPO3 core update can also be found on the official TYPO3 website.

Upgrade-Assistent

After the TYPO3 core update, the Upgrade Wizard can be carried out. You can access it by opening the installation tool via example-website.com/typo3/install.php. The upgrade wizard guides you through several steps, starting with the creation of missing database tables and fields. All updates can also be carried out in the command line.

Some steps in the Upgrade Wizard contain functions that may not be needed and should not be carried out.

Analyze database

After the upgrade, you should go to the maintenance module and use the option to analyze the database. The results show a list of changes, almost all of which can usually be carried out. Special attention should be paid to tables that are no longer required. You should check whether these can really be removed.

Last steps

The language packs should be updated in the maintenance module. It may be necessary to reset the user settings in the same module. In any case, the cache must be emptied under Maintenance and temporary assets must be removed in the Install Tool using the Clean Up option.