I have experienced the same issue with Ubuntu 19.04, 19.10, and 20.04 installers. The system does not boot after the error message. Setting "efi_no_storage_paranoia" from [1] does not seem to help and the syslog does not seems to contain useful info other than the "Operation not permitted" error.
[1]: https://unix.stackexchange.com/questions/379774/grub-installation- failed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1872212 Title: grub-install: Operation not permitted To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2-signed/+bug/1872212/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
