[Bug 1898022] Re: grub upgrade 18.04->20.04 loses dual-boot to W10

[udippel]

Writing my bug report earlier, I was under the impression, the matter
would have to make with an abnormal upgrade to 20.04; earlier two W10
boot partitions, and what not.

I own two identical lenovo Helix 2; and just upgraded the second one.
NOW it IS a bug: because this time, despite of a very normal and
standard upgrade from 18.04, gone through smoothly, after the reboot
also here the grub boot menu is gone, and the device boots by default
into Linux. The only chance to boot to W10 is by interrupting the boot,
and select the W10 partition through the BIOS.

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https://bugs.launchpad.net/bugs/1898022

Title:
  grub upgrade 18.04->20.04 loses dual-boot to W10

Status in grub2 package in Ubuntu:
  New

Bug description:
  (Summary says it:)

  Upgraded by dual-boot kubuntu 18.04 to kubuntu 20.04. After the restart, dual-boot was gone, and it boots directly into kubuntu. 
  I guess it is a problem with grub, because the boot menu doesn't show. However, the 'lenovo' shows trice, while it used to show once with 18.04; followed by the grub boot menu. 

  I guess that the MBR was written into haywire?

  ProblemType: Bug
  DistroRelease: Ubuntu 20.04
  Package: grub-efi-amd64-bin 2.04-1ubuntu26.4
  ProcVersionSignature: Ubuntu 5.4.0-48.52-generic 5.4.60
  Uname: Linux 5.4.0-48-generic x86_64
  ApportVersion: 2.20.11-0ubuntu27.9
  Architecture: amd64
  CasperMD5CheckResult: skip
  CurrentDesktop: KDE
  Date: Thu Oct  1 11:34:39 2020
  InstallationDate: Installed on 2019-03-14 (566 days ago)
  InstallationMedia: Kubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
  SourcePackage: grub2
  UpgradeStatus: Upgraded to focal on 2020-09-29 (1 days ago)

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