Attention

TYPO3 v8 has reached its end-of-life March 31st, 2020 and is not maintained by the community anymore. Looking for a stable version? Use the version switch on the top left.

You can order Extended Long Term Support (ELTS) here: TYPO3 ELTS.

Clear Caches and User Settings

You should always clear the cache tables. Go to "Clean up", scroll down to "Clear tables" and select the tables beginning with "cache_". Then press "Clear selected tables".

You might also consider clearing the Backend user preferences. This can avoid problems, if something in the upgrade requires this. Go to "Clean up", scroll to "Reset user preferences" and click "Reset backend user preferences".