Error updating latest 15.0.6 version

get this error trying to update manually

pi@nextcloudpi:~ $ sudo -u www-data php /var/www/nextcloud/occ upgrade Nextcloud or one of the apps require upgrade - only a limited number of commands are available
You may use your browser or the occ upgrade command to do the upgrade
Set log level to debug
Turned on maintenance mode
Updating database schema
Updated database
UnexpectedValueException: The files of the app “files” were not correctly replac ed before running the update
Update failed
Maintenance mode is kept active
Reset log level

How can i solve this?