TYPO3 Core

During the upgrade from an TYPO3 8 page to the current 9.5-dev version (last commit ab48937e3e3507cb0cec691e0773b49b1006c18c) the upgrade wizard offered to install the extension typo3db_legacy. I installed the extension and after that the message "Something went wrong" comes up and no further wizard worked any more.
The following message was logged:

Got error 'PHP message: PHP Fatal error:  Class TYPO3\\CMS\\Typo3DbLegacy\\Updates\\DbalAndAdodbExtractionUpdate 
contains 6 abstract methods and must therefore be declared abstract or implement the remaining methods 
(TYPO3\\CMS\\Install\\Updates\\UpgradeWizardInterface::getIdentifier, 
TYPO3\\CMS\\Install\\Updates\\UpgradeWizardInterface::getTitle, 
TYPO3\\CMS\\Install\\Updates\\UpgradeWizardInterface::getDescription, ...)
in typo3conf/ext/typo3db_legacy/Classes/Updates/DbalAndAdodbExtractionUpdate.php on line 124

After I disabled the extension the remaining wizards started working again.