Since the Sub is ‘bonded’ to your soundbar of some type in one room, and the One SL in the other room, I would power cycle all speakers in the ‘room’ that have a Sub in them. 
 

I’d also be tempted to give the Sub extra time to finish updating. You haven’t said which generation of Sub you have, but I often wait an extra half an hour to an hour from when it says it is done before double checking. The gen 1 (and 2, for that matter) has such a slow CPU in it, it seems to take a while, and the controller doesn’t seem to wait. I also have this issue with other ‘older’ devices, where the controller seems to ‘finish’ before the device does…if I wait a few extra minutes, I get the ‘all devices are updated’, whereas if I check immediately, I get the ‘failed to update’ error. I’ve found that allowing them to update on the schedule I have set in the controller (I think I have it set for 4AM), it takes care of it without intervention or worry from me. 

I appreciate you for coming back to me, Bruce.

Sorry, the 2 Subs that are in different rooms to each other are both Gen 3. Everything is shown in the chart below

MAIN ROOM
------------------
Playbar
Sub (Gen 3)
Play 1
Play 1
------------------
ROOM 2
------------------
Sub (Gen 3)
One (Gen 2)
One SL
------------------

Going by your first suggestion, you are advocating that I disconnect all Sonos components. Seeing as I am disabled, I will have to get someone to do this for me.

I am also confused with your comment that you said “I’d also be tempted to give the Sub extra time to finish updating.” What did you mean by this?

Did you mean when I unplug each Sub, I should leave it 1 hour before I plug it back in again and then try the update? The same with the other devices?

Can you please tell me with step-by-step instructions how to set the controller to 4 am?

If I am barking up the wrong tree with any of these suggestions, please tell me in greater detail what you actually mean? Thank you.

HB

Sorry. What I meant by that statement is it feels to me as though the controller itself doesn’t wait for the Sub to finish the process if running the update itself, and reports a ‘failure’ as the Sub is still running the update, and hasn’t ‘finished’ yet. This seems to occur on other ‘older’ speakers sometimes, as well.  So when I check immediately in the controller for updates, it still finds that certain devices need one. However, if I wait for a period of time, and then check, the process has actually finished, and I get told that everything is current, and no updates are needed. What I’m suggesting here is that rather than ‘believing’ these errors, and then checking for updates immediately, and applying them, is to leave the process alone for an hour while it is running. Temporarily ignore those ‘error’ codes. Let the process complete before checking, by ignoring it for a couple of hours before confirming by checking for new updates again. 

Alternately, set up ‘automatic updates’ to the speakers while you sleep. In the S2 controller, go to the gear icon in the top right of the controller, then click on “manage”. Then click on ‘system updates’ (this may require scrolling down, depending on your device), then turn on the slider button for “update automatically”. Mine is already on, so I’m not sure if there is currently an option that will come up for setting a time, but even if not, I’d make sure that this setting is turned on, and let the system itself worry about updating the speakers.

As a side note, since much of what I listen to is a randomized local playlist, stored on my NAS, it resets the playback position to one song when the firmware updates. To me, only mildly frustrating, but it does give me a “tell” when the firmware process has been run on my speakers. Still plays the playlist, and each ‘room’ randomizes differently, as I expect, but it does return to the same ‘starting song’ in the playlist.