Update: A fix has been released and you should be able to upgrade to Ubuntu 21.04 now.
Ubuntu 21.04 is already available for download, if you missed the news.
However, no matter how exciting the release is — it seems to have some serious issues for some users. Especially, if you have an older system to use it with.
Ubuntu 21.04: Upgrade Bug
Originally spotted by omg!ubuntu!, this bug does not let you boot into the system after upgrade.
Technically, systems with an early version of EFI will be affected by this if they upgrade to Ubuntu 21.04.
As one of the affected users mentioned in a bug report:
The latest update on Hirsute made the MacBook Air from 2012 unbootable.
It could be recovered by booting a 20.04 live CD, downloading 20.04’s shim package and overwriting the files in EFI/ubuntu and EFI/BOOT with the files shipped in the shim package.
And, this is why you probably did not notice an update notification while using Ubuntu 20.10. Ubuntu developers have acknowledged the severity of this issue and decided not to prompt updates till this bug is fixed.
As the bug report also mentions a solution where you download Ubuntu 20.04’s shim package to make amends.
However, this is not a feasible solution for users.
Ubuntu developer Brian Murray also mentioned more about it in the mailing list:
I wanted to let you know that users of Ubuntu 20.10 are not being prompted to upgrade to Ubuntu 21.04.
Subsequently, upgrading to Ubuntu 21.04 still requires running do-release-upgrade with the ‘-d’ switch. This is due to a bug with the current version of shim in Ubuntu 21.04 which can cause systems with an early version of EFI to fail to boot after the upgrade. Due to the severity of the issue we shouldn’t be encouraging people to upgrade at this point in time. After we have a new version of shim signed will make it available in Ubuntu 21.04 and then enable upgrades.
Shim is a bit of code that is signed by Microsoft. So, they are waiting for the process to complete in order to include the new shim binaries for Ubuntu 21.04.
Of course, it also affects some other official Ubuntu flavours like Kubuntu.
For now, you might want to wait to get the update notification on your system to upgrade it or simply keep an eye on the bug report to be resolved.
Have you experienced this issue when trying to upgrade your Ubuntu system? Let me know your thoughts on this!