FAT-fs (vda15): Volume was not properly unmounted. Some data may be corrupt. Please run fsck

Operating system Ubuntu Linux 20.04.3
Webmin version 1.984
Usermin version 1.834
Virtualmin version 6.17-3
Authentic theme version 19.84.7
Digital ocean droplet

Recently I have been seeing this in my syslog:
FAT-fs (vda15): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.

This shows up in my logs before my recent OS upgrade.
I thought it was speaking about my main disk, but after checking in Virtualmin:

VirtIO device A
Partition Details
Location	/dev/vda	Device file	/dev/vda15
Type	Windows FAT32	Extent	21 - 446 of 205603
Status	Mounted on /boot/efi as vfat	Size	108.58 MiB
Partition name	msftdata
This partition cannot be changed as it is currently in use or configured for use.

The oldest file in there is dated around the time the droplet was created.
e.g. /boot/efi/boot/grub/grub.cfg

# CLOUD_IMG: This file was created/modified by the Cloud Image build process
search.fs_uuid cd899ca9-1943-46c8-9c55-42fc136ef940 root hd0,gpt1 
set prefix=($root)'/boot/grub'
configfile $prefix/grub.cfg

I wrote to digitalocean and they are playing dumb about the existence of such a mount.
Does this mount have something to do with Virtualmin?
And what should I do about the warning message?

No. Definitely not.

Was there a USB/flash disk plugged in at some point?

My VPS is a digitalocean droplet. I am not able to plug in a USB. Also I never mounted any filesystem to it.

Anyway, I checked this page: installation - Is it safe to format msftres, msftdata and hidden partitions? - Ask Ubuntu

  • msftdata – This flag identifies a Microsoft Basic Data partition. It normally holds a Microsoft filesystem, like FAT or NTFS, so such partitions will include your C: partition and perhaps recovery or data partitions. You should not delete or change them unless you understand precisely what type of data is on the partition and want to delete it. Note that Linux used to use the same type code for its own partitions, so you might see this flag on a Linux partition, too. Two years ago a new Linux-specific type code was created, and Linux partitions with that type code will show up as having no flag set. Versions of libparted that recognize the new Linux-specific type code are only just becoming available. The “msftdata flag” appeared with that same new version of libparted.
    Note also that libparted uses the same “flag” concept to identify two entirely different data structures: partition type codes and partition attributes. Type codes are mutually exclusive; a partition can be an ESP or a Microsoft Basic Data partition, but not both. Thus, if you remove the “boot flag” on an ESP, it will likely pop up with an “msftdata flag,” since ESPs use FAT, and FAT partitions get the “msftdata flag” by default. (In older versions of libparted, the “msftdata flag” doesn’t exist, so the partition would have no flag.)

Looks to me like some mistake/mis-recognition of the partition?
So I went ahead and just …
fsck.vfat -v /dev/vda15
and now it is clean and not complaining.

At least finally I got a decent reply from digitalocean support. As I thought it seems to be a mis-labeled partition…

Yes, this partition is a part of the Ubuntu installation. It is the boot partition for your Ubuntu Droplet. This is created when the Droplet is created. I am not sure why fdisk shows this partition as “Microsoft basic data” but that is not accurate as it is necessary to boot Ubuntu.

If you received errors for this disk, I would recommend trying to find a way to repair them as it could impact your Droplet bootup in the future.

You can find more about this partition here:
[ubuntu-cloud] Cloud-images: Announcing UEFI and BIOS/GPT images for Trusty

I found this article that might be helpful if you do need to fix corruption:
Recover from a badly corrupt Linux EFI installation

Please let us know if there is anything else we can assist you with!

Kind regards,
DigitalOcean Support

Created by their build. These are automated. Their feedback sounds reasonable. Image may have got corrupted during install or later. Its rare but can happen. Either way you solved it yourself and that must be a good feeling. Happy days :+1:

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