I just upgraded my xubuntu box to 21.04 as well with a very similar problem. In my case the message is "error: sparse file not allowed" and a second later "Press any key to continue...". With no key stroke, it will time out and continue after a few seconds.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2065476 Title: During boot, after grub selection screen, it appears "error: sparse file not allowed - Aborted. Press any key to exit." To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/2065476/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
