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Lenovo P1 was running ubuntu 20.04 fine since early 2020. Specific issue now - no boot loader found in MBR from boot repair report at

https://paste.ubuntu.com/p/GnWFPBnsJV/

Cause: i used P1 laptop booted with install usb drive for 20.04.1 to install ubuntu on a different usb drive to boot a different laptop which was having issues. The first time i tried the experimental zfs root install and the drive I was installing to was empty according to gparted. I reinstalled that 2nd usb drive with ubuntu a second time and it works as a boot drive on the alternate laptop. However the P1 does not boot using nvme0n1 the drive which has ubuntu on it. Using bootrepair I discovered that MBR had no bootloader any longer. The P1 has a second ssd nvme1n1 with windows 10. Booting that works fine and should not be relevant to this discussion.

Boot repair report is located at

https://paste.ubuntu.com/p/GnWFPBnsJV/

I do not see how to reinstall just the boot loader to MBR on nvme0n1. I have backups of personal data so worst comes to worst I can reinstall and restore. However not all data is saved and historical backups were on a zfs filesystem which I cannot recover without getting the system back. So can the boot loader be reinstalled without affecting the rest of the install?

Thank you.

Len Zaifman
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    With UEFI systems, you are not supposed to have an old BIOS boot loader in MBR. Protective MBR only exists with gpt partitioned drives, for one gpt boot entry, so old partition tools that only read MBR, do not try to modify drive & damage the gpt drive. Can you boot both Ubuntu & Windows directly from UEFI boot menu? And you should always only boot in UEFI mode including any & all repair tools. And all drives should be gpt partitioned. – oldfred May 06 '21 at 20:10
  • As far as I can tell: – Len Zaifman May 08 '21 at 21:32
  • Is issue that creating full install on external drive? You have to create gpt partitions with an ESP anytime you install Ubuntu to an external drive. Posted work around to manually unmount & mount correct ESP during install #55 or( #23 & #26) https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1396379 Second drive https://askubuntu.com/questions/1296065/dual-booting-w10-ubuntu-with-2-separate-ssds-in-uefi-mode/1296153#1296153 & https://askubuntu.com/questions/16988/how-do-i-install-ubuntu-to-a-usb-key-without-using-startup-disk-creator/1056079#1056079 – oldfred May 08 '21 at 21:52

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