snap-store --quit && sudo snap refresh snap-store
I too ran into the same issue. I was only able to update snap-store (Ubuntu Software) by running:
killall snap-store
sudo snap refresh snap-store
The last versions of SnapStore include a parameter for that
@SergioCostas I tried the command you suggested, but as of version “41.3-66-gfe1e325”, it doesn’t look like it’s working or available yet.
$ snap-store --quit-on-close-for-update
snap-store --quit
snap refresh snap-store