After a Mint upgrade to 19.3, GRUB no longer worked on my workstation. I found a work around by booting a GRUB CD, selecting the option for LVM support and then picking the option to display the kernels. I can then boot the kernel that I want. Boot Repair was not able to fix the issues. Update Manager has worked in the past but the GRUB post processing causes errors. Recently, I decided to remove some of the many kernels to simplify the system. I could not remove the kernels and I am now having issues installing software. I really need to address the root cause of the issues which are the challenges with GRUB. I do not want to re-install the system as there is a lot of software and configuration that would be hard to duplicate. I tried posting to the Mint forums but received no help. Are there any GRUB experts out there who could help? Thanks in advance.
Good choice, to attack the root issue. However, is GRUB really the root cause? What exactly is causing GRUB to misbehave?
From what I’ve read, there might even be a chance that your issues will stop happening after a clean installation.]
I understand this very well, but if this machine is so important, you perhaps need to be prepared to re-install it more than once. I would recommend you some type of back up, so you have an easier time setting up your system with all the configuration it needs.
If you have to re-install constantly to fix problems, we have recreated the biggest issue with Windows. Linux/Unix systems should not have to be re-installed to fix them. There are usually solutions to the problems and I am sure someone who is familiar with GRUB and the update process in Mint could easily fix mine. GRUB failed after the upgrade probably because of LVM. Using some oneline posts I have finally figured out how to boot the system from the GRUB prompt (versus the GRUB boot disk I was using). Here are the commands:
grub> set root=(lvm/mint–vg-root)
grub> linux (lvm/mint–vg-root)/boot/vmlinuz-4.15.0-158-lowlatency root=/dev/mapper/mint–vg-root
grub> initrd (lvm/mint–vg-root)/boot/initrd.img-4.15.0-158-lowlatency
grub> boot
I still cannot bet boot repair to fix GRUB though. I will have to be done manually. Update used to work as well although it always had trouble configuring GRUB. I tried to remove a lot of the old kernels that caused the update process to run a long time and now it is failing with a “Too Many Errors” message. I really think if we could fix GRUB and get rid of the unnecessary kernels that the system would be fine. Everything else works now but there were a lot of challenges with printing and the specific printer I use and setting up the Digital Audio Workstation (DAW) etc that I don’t want to get back into …
Sorry for the typos, I meant “I still cannot get boot repair to fix GRUB though. It will have to be done manually.”
I am a bit amazed that no one could tell me the commands to boot from the GRUB prompt with LVM and I had to figure them out. I will post this in the Mint forum so others know. This should be a common setup, I would think. Boot Repair also has questions about RAID but nothing about LVM. On the boot disk the option to setup support mentions both LVM and RAID. Selecting this option works for me. Also, I don’t understand why I need to go through Update Manager to get rid of the old kernels. Since they are not used there should be a simple process to delete them and then correct the update manager index.
There are always solutions to all problems. Like e.g. just getting one asteroid to mine ores from would be extremely helpful for the whole humanity. However, things aren’t as easy.
It’s just easier to re-install the system. Not only easier, though.
Most importantly, it saves a lot of human life time and human resources. This is the most important thing in humans’ lives.
So, it’s usually not only more comfortable, but simply better to re-install the system, because it saves a lot of headaches. Sure, setting up your system the way you want to takes time and effort too, but at least you know what you are doing and aren’t just poking around, trying to find the root cause of an issue, by trial and error. Trying to solve such issue could take an infinite amount of time, especially when a lack of expertise and knowledge among the ones who are trying to solve that issue, is apparent.
So, while, in theory, you are correct, it’s not the real “fix”, but it’s most of the time commonly the best overall workaround for getting such issues fixed. Especially if you have work to do.
P.S.:
Such a re-installation could even prevent further problems. So, even if you fix that one issue, another one might arise, for whatever reason. Re-installation usually minimises the chance of such issues arising, except your are upgrading your OS when re-installing it.
I think your troublesome journey and strict refusal of a simple re-installation proves the point made in my previous response. 
This is why things do not get fixed in the Linux Desktop community and one reason why it has never achieved any market share there. Suggesting re-installing does not solve any problems and does not move things forward. It gives the user the impression that there is no way to get help (which is unfortunately true in many cases). At some point I will probably install a newer version of Linux on a different machine but with just a little help from someone knowledgeable about GRUB and the Mint Upgrade process these issues should be fixable.
Ouch, this is so wrong and can simply be disproven by the fact that the most popular consumer distribution on earth is the one which you re-install on every hiccup.
The real reason why Linux has such a tiny market share among end consumers is because Linux elitists don’t give a single hovering fuck about end consumers. They do everything on their high horse and do not care about non-techy people.
Oh, what’s that? You have a simple problem, that you can solve within 1 minute on Windows, without any technical knowledge?
No problem! Just learn a scripting language like Bash or whatever and write a script.
Oh, what’s that? Our new Kernel makes your GRUB fuck up, so you can’t boot?
No problem, just fiddle with your OS low level settings for a while and then write a script to “fix” it until the next Kernel issue manifests.
This is what keeps the market share so low. Not the fact, that people have to re-install anything or are forced to update.
Right. You need to find an expert. Unfortunately, I am very new to Linux. Have barely any idea about it and am just pulling statements about it out of my arse. 
I am finding clues on how to fix it. Seems like there are even theme and font issues with Mint 19.3 for GRUB that are contributing to the issues. I will try to work my way through them and document what I find.
That might indeed help future readers, in case they experience the same type of issue. This is appreciated. 