Also downloading and installing the official 1.7.1 works (as indicated here: Updated Corona Contact Tracing Germany from Apps fails and originally here: https://codeberg.org/corona-contact-tracing-germany/cwa-android/issues/51#issuecomment-165230)
Also downloading and installing the official 1.7.1 works (as indicated here: Updated Corona Contact Tracing Germany from Apps fails and originally here: https://codeberg.org/corona-contact-tracing-germany/cwa-android/issues/51#issuecomment-165230)