found a workaround for the problem caused by new Sonos controller app when adding a new speaker

Same here.. any update SONOS team?.. this is so frustrating for an expensive equipment. 

Check the update on the app store.. SONOS released an update on July 4th.. I applied it and now is working.

1.- open your app store and make sure the app is up to date (there is an update released on July 4th solving the issue)
2.- after doing the update, let's  please do a factory reset in your speaker. Factory Reset Instructions for Sonos Devices: Because we will need to re-add it.
3.- We will need to perform a factory reset on your Sonos device  will erase all internal information, including registration details, My Sonos content, and music services. This process allows you to add the device to a new system or existing one. Follow these steps carefully:
4.- Unplug the Power Cord: Disconnect the power cord from the Sonos speaker or component you wish to reset.
5.- Enter Reset Mode: Press and hold the "Join button (∞)" on the device.
6.- Reconnect Power: While holding the button, reconnect the power cord to the Sonos device.
7.- Continue Holding: Keep holding the button until you see the light on the device flashing orange and white.
8.- Completion Indicator: When the factory reset process is complete, the light on the device will flash green, indicating that it's ready to be set up again.

Follow these steps precisely to ensure a successful factory reset of your Sonos device.  

9.- Then, when the speaker gets the flashing green light, please re-add the speaker following these steps.
Steps to add a speaker to the system. 
 1. Open the Sonos app
 2. Navigate to Settings. Under Products, select Add Product.
 3. Follow the on-screen prompts to add a new Sonos product.

That kind of worked. 

The update got me further, seemed to go through the set up correctly. 

But now I am stuck on "Unnamed room is not connected". Very frustrating. 

man this was such a pain.. took me hours.. but finally this is how it worked for me:

Background :

1. I have ARC + Base + 2 Sonos one as a Home theatre
2. I have 4 other Sonos one
3. and a sonos move

I changed my router and thus the wifi was changed. all hell broke loose..nothing was working. I added the ARC and then I added the base. but the moment I was adding base to ARC, the app was crashing. I use IOS.

finally this is the order in which it started working

1. I unplugged all speakers
2. I transferred the ownership from the new app to myself
3. then I added ARC
4. then I added 2 Sonos one and made them pair with ARC. I did after factory reset ( unplug -- keep the button behind pressed and plug in power while keeping the button pressed. let the lights change, they change from white to orange and finally Green blinking). when the lights were blinking I selected “add a new speaker” and thats when the app detected the speaker and added it 
5. then I added the base. -- then app did not crash. I did after factory reset (as described above). I feel that if base is added directly after the arc, the mess happens
6. then my home theatre was complete
7. after that I plugged in each of the 4 other Sonos one, one by one using same reset
8. finally all was restored.

I hated this process as it wasted literally hours of mine, to figure out how to make it work.

Sonos should fix this immediately. when we pay hundreds of dollars for the speakers, then this is not what is expected. hope this helps some of you. and saves a few hours to

This worked for me as well! Thank you!

P.S. it’s ridiculous Sonos launched an app that broke everyone’s systems and still hasn’t fixed it 3 months later!!!

I tried this and it still does not see the second speaker I have successfully added (allegedly). Should I factory reset the first speaker and start all over again? 

I have spent the better part of today trying to set up a pair of Play 1’s for a rental flat. As this entailed factory reset and setting up a new system I quickly ran into the problem described. I of course took all the blame initially thinking it was my phone, my WiFi, my router or a problem with my speakers. It most likely has been Sonos app all along.

I must say, this is very disappointing for a company that used to be the gold standard. I used to work in software development and enterprise software management and I know it really takes a proper good effort to screw things up so thoroughly. Sonos seem to be failing at all levels, be it management, architecture, development, testing and release management. This takes a special kind of STUPID.