Grub doesn't work

[oldfred]

Post link to new summary report from Boot-Repair.

[sheine]

http://paste.ubuntu.com/26368286/

[oldfred]

Is drive set for AHCI?

I do not really see anything wrong.

Did you verify your download of Mint was valid.
https://help.ubuntu.com/community/HowToMD5SUM

[sheine]

The drive is set for AHCI.

[oldfred]

If Ubuntu works and Mint does not, then I would suspect something wrong with your copy of Mint.
Try redownloading it, check its md5sum or use zsync to download to existing ISO which will automatically verify it is correct.

Zsync is in Ubuntu repository:

zsync is a file transfer program to download files from
remote web servers. If a previous version of a file is available
locally, zsync will only download changed parts and hereby
minimise the download volume.

example of commands, but do not know Mint local mirror for you, or name of Mint ISO.
I have all my ISO in an ISO folder in /home
cd ISO
zsync http://cdimage.ubuntu.com/daily-live...md64.iso.zsync
zsync http://mirrors.gigenet.com/ubuntu/16...md64.iso.zsync

[sheine]

I downloaded a new copy of Mint with md5sum, installed it as before and ended up with the same two errors when I tried to load Mint from grub.

[oldfred]

I thought newer systems with AHCI did not have this issue.

https://ubuntuforums.org/showthread.php?t=2239624

You may need to add a /boot or make both installs have / (root) partition in first 100GB of drive.
I typically install in 25GB / (root) partitions, and then have a large ext4 shared data partition mounted at /mnt/data.
And issue depends on where on drive grub & kernels are installed, which normally is random. So system may work until you get an updated kernel and its further into partition.

[sheine]

I tried something that failed but may give you a clue. On my other computer of the same year as the Dell, I successfully installed Mint a while back. I now downloaded the same version of Mint, Petra, and installed it. In this case, grub gave me a different error message: Kernel panic-not syncing: Unable to mount root fs on unknown block.

[oldfred]

It seems like the same kind of issue.
Are you installing in one very large / (root) partition.
You want a smaller / partition of 25GB for every install and keep that inside the first 100GB of drive. Then rest of drive can be separate /home partition(s) or large data partition.

[sheine]

The Ubuntu boot that I am using is grub 2.02. Can I get into any trouble by reinstalling Mint and using its boot loader rather than the Ubuntu loader on sda1?