I am trying to upgrade from Typo3 6.2 to a later version (to be determined). When I run the Core Update in the install tool the 'Fetched list of released versions' works, however, it is then followed by a 'General error'. In the log, this is the error:
Core: Exception handler (WEB): Uncaught TYPO3 Exception: #1380898792: No version matrix found in registry, call updateVersionMatrix() first. | TYPO3\CMS\Install\Service\Exception\CoreVersionServiceException thrown in file /home/usr/public_html/typo3/sysext/install/Classes/Service/CoreVersionService.php in line 271. Requested URL: https://domain.dev/typo3/sysext/install/Start/Install.php?install[action]=importantActions&install[context]=backend&install[controller]=tool&install%5Bcontroller%5D=ajax&install%5Baction%5D=coreUpdateIsUpdateAvailable&_=1608549770287
I have looked around for ages and can't find a fix that works. I will be very grateful for any help, please.
I don't think that you can update such an old Version by the install-tool update mechanism any more. since that version a lot has changed.
newer versions of 6.2 are only available as paid service (ELTS) from the TYPO3 GmbH.
And I think the server structure also changed meanwhile so that old ULRs might fail.
your way of update should be a manual update to (any outdated version of) 7 LTS, then the same for 8 LTS until you come to 9 LTS and 10 LTS
on each version do the upgrade wizards and fresh up the extensions if possible (including the upgrade wizards of the extensions).
individual extensions need their own updates.
use the deprecation log on each version to identify possible failures for the next TYPO3 version.
somewhere between you might change the installation to composer installation, which will result in a cleaner update way (if you are familiar with composer). for the future it will be very helpful to understand composer.