Purging snapd fails due to the hunspell mount

[Alkis Georgopoulos]

Purging snapd fails with "Read-only file system" errors due to the hunspell mount.
Workaround: run `snap remove firefox` before `apt purge snapd`.

Failure sample:

# apt purge snapd

The following packages will be REMOVED:
  snapd*
...
Removing snap firefox and revision 1635
rm: cannot remove '/var/snap/firefox/common/host-hunspell/en_GB.dic': Read-only file system
...
dpkg: error processing package snapd (--purge):
 installed snapd package post-removal script subprocess returned error exit status 1
Errors were encountered while processing:
 snapd
E: Sub-process /usr/bin/dpkg returned an error code (1)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Mario (mario-gleirscher)]

A few weeks ago, I removed the firefox snap and replaced it with firefox deb. The snap removal with
sudo snap remove firefox
caused an error message mentioning a mount to the hunspell directory. I ignored that for the time being.

Because snap is continuously reminding me of updates, I also wanted to remove snap entirely with
sudo apt purge snapd
as nicely discussed at
https://askubuntu.com/questions/1280707/how-to-uninstall-snap

But then I got the above error message. What can I do instead of waiting for a bugfix, given that is a bug in the first place?

The discussion at
https://forum.snapcraft.io/t/sdb5-mounted-on-firefox/31897
was somewhat helpful to understand the complexity of that problem but didn't help me much in figuring out what to do.

So, how can I remove the block device manually, especially when it's mounted at the same point as
my root?

nvme0n1 259:0 0 476,9G 0 disk
├─nvme0n1p1 259:1 0 953M 0 part /boot/efi
├─nvme0n1p2 259:2 0 16M 0 part
├─nvme0n1p3 259:3 0 39,1G 0 part /var/snap/firefox/common/host-hunspell
│ /
├─nvme0n1p4 259:4 0 342,2G 0 part /home
├─nvme0n1p5 259:5 0 67,9G 0 part
├─nvme0n1p6 259:6 0 613M 0 part
└─nvme0n1p7 259:7 0 15,6G 0 part [SWAP]

[Alkis Georgopoulos (alkisg)]

While waiting for an answer from the developers,
I would suggest that you try the following:

sudo snap install firefox
sudo snap remove firefox

I assume that the older firefox that you had, had uninstallation issues, which were solved in the more recent version that I tested with.

If that doesn't solve the issue, only then do:

sudo umount /var/snap/firefox/common/host-hunspell

This will manually disconnect the mount, but it won't delete the service from /etc as uninstalling firefox does.

And at that point, you'll be able to do:

sudo apt purge snapd

[IGHOR (julyighor)]

@alkisg this does not helps.
While I was able to uninstall snapd after umounting the path, it is still re-mounted after reboot.

[Alkis Georgopoulos (alkisg)]

@IGHOR, so you ran `sudo snap remove firefox`?