Unable to boot from my droplet's hard drive (CentOS)

I have been at this for days without any solution. I’ve been back and forth with DO support, but they have been unable to help me.

My droplet is using CentOS 7 (RHEL). In the Recovery section in my Droplet’s settings, when I try to boot from the hard drive (selecting the ‘boot from hard drive’ option), I checked my DO web console and I get this error:

error: symbol 'grub_calloc' not found.
Entering rescue mode...
grub rescue>

I’ve had a dozen browser tabs open with websites and articles, and have exhausted Google trying every suggested solution I could find. A lot of the solutions were for Ubuntu, so I was trying to find the CentOS equivalent, or just try the steps anyway and hoped they worked. I have not worked with Ubuntu as much. These are the things I’ve done:

• Powered off/on the droplet
• Power-cycled the droplet
• Went into recovery mode, mounted the disk (option 1), then went to the chroot option (option 5)

From there I did these things that I’ve found all over the internet:

1. Checked my kernel by typing umame -sr It returned: Linux 4.15.0-23-generic

2. Updated/upgraded the kernel (dnf update kernel, dnf upgrade kernel)

3. Tried installing an older kernel

4. Updated/upgraded grub (Grub2 on CentOS 7)

5. Reinstalled Grub

6. Ran this command to see all of the CentOS versions that are installed on the disk: awk -F\' '$1=="menuentry " {print $2}' /etc/grub2.cfg

These are the two entries I have:

CentOS Linux 7 Rescue [long alphanumeric string] (3.10.0-693.17.1.el7.x86
CentOS Linux (0-rescue-[long alphanumeric string]) 7 (Core)

7. Attempted to mount the boot partition (it’s located on /dev/vda15). I typed: mount /dev/vda15 I got an error: mount: can't find /dev/vda15 in /etc/fstab

8. Set the Boot Default in Grub. I only had two versions to choose from (see step 6). I typed: grub2-set-default 0 the powered down the droplet, switched to boot from the hard disk, then powered it up again. I still got the ‘Grub Rescue’ screen. So I powered the droplet back down, switched to Recovery mode again, powered up, and tried the other boot option: grub2-set-default 1 Rinse and repeat with the power up/down the droplet, and I still got the Grub Rescue screen.

9. Tried grub2-mkconfig which was a popular solution everywhere, but this was the error I kept getting when I typed that:

/usr/sbin/grub2-probe: error: failed to get canonical path of 'overlay'

I couldn’t for the life of me find that error anywhere on Google or any searches where other people had that same error. There was a similar one about it not being able to get the canonical path of ‘/cow’, but I couldn’t determine if it was the same issue I was having.

I’m at a loss of what to do. I can’t seem to get my droplet to successfully boot from the hard drive. I am able to get into my files and things when I boot through the Recovery Mode, but I don’t want to keep my droplet set on Recovery Mode forever. I have a lot of websites connected to this droplet.

Is there anything I can do to fix this? Or will I have to completely destroy the droplet and rebuild? I just don’t want to lose everything. I have databases and things that I need to preserve. I already took a snapshot of my droplet as soon as this problem happened. I am hoping to be able to fix the hard disk’s boot sector and migrate my droplet data back.

Thank you in advance for all your help!!