Your message is a little confusing, but it sounds as if you need to update the OS version of your S1 system, before you can add any new speakers to it.  Sonos recently added a security patch to S1, so it makes sense to require that update.

  It’s an ‘update’, not an ‘upgrade’ to S2, if that was the confusion.  If your just update that you have to keep your Sonos S1 system up to date when you add new speakers to it, not sure what to tell you. 

So your update isn’t working when i press update.Is this another ploy for everyone to buy more products or am i gonna spend another day chasing you and ringing you about a system that worked perfectly well before this weekend?

Have you tried shutting down and restarting the app?

Yep it wont work and i have 2 systems which are newer that it wont pick up.Wont let me add them because the add a system is in light grey and still sais update

What mobile Controller (operating system) are you using? - does it meet the system requirements shown here (see link to ‘App requirements’)... 

Sonos System Requirements

Hmm..  Just to confirm, your S1 is not yet on version 11.2.6?  Does your iphone or android meet the required version?

https://support.sonos.com/s/article/4941?language=en_US

Hi GlendaC4S…

                           I had exactly the same problem as you for the last day !!!!! I could not sort it out either.

I called sonos support first thing this morning……….. Every thing is now fixed and working on the S1 controler as before.

Same as you i have a mix of S1 & S2 devices.

The fix is ,,,,,,

Ensure you mobile device is on the same wi-if network as your Sonos system to start with.

You need to Re set any S2 speakers back to default. ( Hold in button on the back when you plug in to mains and keep held untill flashes first orange then green ...I think )

Launch the S1 controler app then go to ( as you have said ) settings

Then system tools

Then system compatability check

You then get the option to upgrade …… OR continue with S1 controler.

This is the one you want…

After all that you shuld notice that the options

add product

add boost or bridge

find missing product

Are no longer greyed out.

You can then re add your speakers…

P.S turn off auto update.

I think this is the correct order…..Is you have problems call Sonos support.

do it first thing in the morning as they are getting LOADS of call for this…

Best Wishes & Good luck..

20 years?  Must own prototypes, because Sonos didn’t have an actual product to the customer until 2005.