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I get this error when updating Akeeba Backup on J4.
0 Pkg_AkeebabackupInstallerScript::postflight(): Argument #2 ($parent) must be of type Joomla\CMS\Installer\Adapter\PackageAdapter, Joomla\CMS\Installer\Adapter\LibraryAdapter given
The version number is correct so I assume the update worked but something postflight must have gone wrong, so I'm not sure if it's entirely updated or there will be a problem.