Flatpak updates don't appear; blank OS Update appears instead
For the past few days for me, Software has been reporting that OS Updates are ready, but the list of which updates are available includes a blank entry at the top. Even after a Install and Restart to install actual updates, the blank entry still exists. Also, when the blank entry is the only update available, a red "Update" button appears in the "OS Updates" section, which implies the update can be installed without a reboot. Also, the button on the top-right corner says "Update" instead of "Install and Restart". Clicking either update button has no effect.
(Imagine that the button is red instead of blue; colours are wrong because of Bug 779234)
Running pkcon offline-get-prepared
shows that no offline updates have been prepared. Running pkcon refresh force -c -1
and restarting Software didn't change anything, either.
Eventually, I realized that the "Update" button in the "OS Updates" section was a lot like a Flatpak app's "Update" button, so I tried running flatpak update
in a terminal. Surely enough, a whole slew of Flatpak apps got updated, and the blank entry in the Updates page of Software went away (after pkilling Software).
What must have happened is that Software's handling of Flatpak updates got messed up somehow, and showed available Flatpak updates as a blank OS Update for some reason.