Huh? Post a screenshot please.

Thanks for getting back to me. Here’s a screenshot

This message “S1 controller isn’t compatible” implies you have already upgraded your Sonos speakers to S2 or you have an S2-only new device. If that is the case then you need the S2 app now. I assume that if you tap “Update” it will take you to the App Store for the S2 app.

If you have NOT already upgraded your speakers to S2 then kill this instance and check the App Store for an update to the S1 app.

I am guessing here because obviously I don’t know what happened to your system prior to this. i also have no idea what “More options” offers.

Identical Issue,  stated in text:

Sonos states that users may continue to use their S1 controller app, instead of upgrading to the S2 controller app, if they do choose. 
However, my S1 controller app is producing the message, “Your sonos s1 controller isn't compatible with your system” and is refusing to control my Sonos system — in which I have all Pre-May 2020 components and with which I have *not* run the S2 controller app and attempted any upgrade.

How can I regain use to my S1 controller and system?

Resolution:  I’d apparently initiated an “upgrade” to S2, by responding to an upgrade prompt In the S1 app, days ago, even though I’d not yet installed the S2 controller. Once I installed the S2 app and logged in with it, I found my old S1 configuration intact and was able to resume playing music.

My bet is that anyone seeing the message, described above, has no choice but to install and begin using the S2 app. I’d refrained from doing so, as I’d read so many S2 upgrade horror stories in the App Store, but I’ve encountered no problems, myself, since unwillingly completing the upgrade. 

It’s much more common to see issues, than it is to see posts from those with no issues. Look at the nightly news programs. Or a hospital. People who are not sick rarely check in to a hospital. 

  The message that hid the rest of the screen stated that our system was not compatible with S1. First of all that was not true. Compatibility tables verified what I already knew: the system was working just fine on s1. Nevertheless I ended up upgrading to S2 only because it was the only way to get around the message off the screen. My intention was to then go back to the Apple store, delete the S2app and reinstall the S1. I ended up not doing that though because S2 is working just fine