If you're upgrading to a new major release or want to update an older TYPO3 system, a manual TYPO3 update is often a good idea. Here, I'll explain how to do it.
There are various reasons for performing a manual TYPO3 update. For example, if Composer is not available on your hosting server and/or you cannot access your web space via SSH, your only option is to update using the installation tool. If—as is the case with the Privat-Plus plan from allinkl—you cannot even extract a *.tar.gz archive, your only option is to update your TYPO3 system manually.
In any case, it is recommended that you back up the files, including the database, before the update and save them to a secure storage medium.
I never perform an update—for example, from version 11/12 or 13 to 14—on the live system; I always do it on a 1:1 copy of the site, often under a subdomain (e.g., dev… or update… instead of www…). That way, the live site can continue to run, and the update doesn’t interfere.
The older the system is, the more likely it is that you’ll find outdated or unnecessary content or extensions. An update is therefore the best opportunity to clean up the system thoroughly. All TYPO3 extensions that are not installed or are not in use should be uninstalled via the Extension Manager and, ideally, deleted right away.
Update all remaining local extensions (located at /typo3conf/ext/<ext_key>/) to the latest version compatible with your TYPO3 version. Then take a look at the “ext_emconf.php” file. Under “constraints/depends/typo3,” you’ll find the TYPO3 versions with which this extension is compatible. For some extensions, you’ll see something like “12.4.0-13.99.99”; in that case, you should be able to update your system from version 12 to 13, for example, without any problems. If it says “only” “12.4.0-12.4.99,” you’ll likely encounter errors after the update.
In the backend, under “Administration Tools,” open the “Update” section. The “Upgrade Wizard” checks all database tables for a complete structure and adds any missing fields or tables. In addition, updates from well-programmed extensions may also be performed there.
After that, under “Maintenance,” you should also