Self-update fails: unable to remove target file [linux too]

Attempting to self-update, the full error message is
Fatal: unable to update restic: unable to remove target file: remove /snap/restic/12/bin/restic: read-only file system
Having just installed restic 0.9.4, I am attempting to update to 0.9.5. A similar problem was reported earlier with Windows, but I am running KDE Neon 5.15 (based on Ubuntu 18.04).
I am looking for a better backup arrangement and want to try restic, but I need some advice as to how to get the current version installed.

Looks like you have installed restic as Snap App. That’s most probably the reason why restic self-update isn’t working. You’d either need to wait for the maintainer of this snap to update it or remove the snap and install restic yourself.

Installing restic yourself is as easy as downloading and unpacking the binary.

# download the binary to the current directory
# unpack the binary (the bzip2 package needs to be installed)
bzip2 -d restic_0.9.5_linux_amd64.bz2
# make the binary executable
chmod a+rx restic_0.9.5_linux_amd64
# move the binary to make it globally available
sudo mv restic_0.9.5_linux_amd64 /usr/local/bin/restic
# check if it was succesfull
which restic; restic version

Note that restic self-update should work again when restic is installed manually.

Thanks for the very clear instructions. Restic is now installed and I shall start playing with it.