[Koha] Onboarding not working for language de-DE

Hello, when I try to proceed with the onboarding process after the installation I get this error: Template process failed: file error - /usr/share/koha/intranet/htdocs/intranet-tmpl/prog/de-DE/modules/onboarding/onboardingstep1.tt: not found at /usr/share/koha/lib/C4/Templates.pm line 122. I've set the language to de-DE. Ubuntu 20.04, Koha 20.05 (lastest from stable channel) Any ideas? How can I reset the language to finish the onboarding? Or do I have to start again? Regards, Stephan