grub corrupted by routine system update -- maybe due to unconventional partitioning

[David Holdsworth]

On two occasions in the last few months I have had to re-install grub after a software update. I think that my disk partitioning is the problem. Here the print from fdisk:
Disk /dev/sda: 298.1 GiB, 320072933376 bytes, 625142448 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x0f8002b1

Device Boot Start End Sectors Size Id Type
/dev/sda1 2046 14667775 14665730 7G 5 Extended
/dev/sda2 14667776 48222207 33554432 16G b W95 FAT32
/dev/sda3 * 48222208 625141759 576919552 275.1G 83 Linux
/dev/sda5 2048 14667775 14665728 7G 83 Linux

Partition 1 does not start on physical sector boundary.

Partition table entries are not in disk order.

The system is in /dev/sda3, sda1 contains lubuntu and there is no operating system in sda2. sda5 has only recently appeared and its existence is a complete mystery. I got grub back by doing a re-install of lubuntu in /dev/sda1.

I am using ubuntu18.04.5 -- and I apply all software updates. (The user interface on 10.04LTS was better)

It is impossible to get any more diagnostics because my machine just offers a blank screen with a blinking cursor in the top LH upon switch on.

[Steve Langasek (vorlon)]

Showing a partition table tells us nothing about the configuration of the grub package and is thus unactionable. Unless you can provide information about the state of the grub package when the system is failing (which is possibly by booting from a live CD and chrooting into your install, instead of reinstalling), there's not going to be anything we can do with this bug.

[Launchpad Janitor (janitor)]

[Expired for grub2 (Ubuntu) because there has been no activity for 60 days.]