error: null src bitmap in grub_video_bitmap_create_scaled

[stschulze1972]

Ubuntu 20.04.3

installed with install-script

grub2-boot-theme is shown, first press on item "other Ubuntu Options" opens the submenue -> Esc -> seconde press on the same item opens black window with "error: null src bitmap in grub_video_bitmap_create_scaled" -> "press any key to continue" -> ubuntu is starting

where is the promlem ...all files at her place