Fix for me was to connect my two MOVE 5 to ethernet, reset both, then add as new system.  

What a crap update!

I had the exact same issues like many of you in this thread when trying go connect my beam to my new network yesterday. When I thought all was set up I came to the “update” page where I was supposed to contact the system owner to make that.

Just now I tried by connecting the beam to my routher via an ethernet cable and it was all set up withing 5 minutes. No question about update or system owner.

I can confirm that my beam is still connected to my wifi and TV after unplugging the ethernet cable.

Me too. I moved and now can’t set up either of my speakers. Serious WTF @Sonos !!!!

This Was The Only Solution That Work For Me Is Well I Have a Mac I Have To Start The Tired PT There den Finish With The Phone or tablet app

Follow This Is The Only That worked From Me From Another member,

Via iPhone it didn’t work for me neither. I solved it via downloading the Sonos app on my MacBook. It worked immediately and as of then, the iPhone app was also OK again. 

So for anyone else having this crash loop, I was able to get the devices to register and update in a fresh install of Sonos app from within an Android phone (it was IOS that was having the issues).  Once the devices were added, registered and updated in the Android device, I erased and re-installed Sonos on the iOS device to get out of the loop, then reinstalled and viola, the devices are all fine now in the IOS App.  The crashing and doom loop seem to be an IOS problem for now. 

Hope this helps anyone stuck waiting for resolution from Sonos.  How they, this many years in, continue to release such god awful buggy software that constantly fails updates, registration, etc… is beyond me.  Thinking of moving to Bluesound just because of how bad the Sonos app system is and how, without fail, it’s going to stop working, need an update, or they are going to have screwed with the app, right when you need it.

Anyway, this solved the new buggy app issue for me with devices.  The problems seem to be with IOS app so bypassing that to register devices is working for now.

I  notice a couple of posters here have fixed the problem by using the MacOS version of the Sonos app. I have the Mac version but cannot see any way to do anything to solve the problem. Can someone who has fixed the issue this way provide the steps which they took to accomplish such a “fix”? 

Found the solution to why it was happening to me as soon as I updated the app. The cause was that I set up my Sonos 8 or 9 years ago with an old email. I logged out of my current email and logged back in with my old email and fixed it in seconds. Hope it helps someone off the cliff.

Thanks but it didn’t work 

The solve actually does work. I’ve been in the Sign In loop for a week.

I factory reset my Sonos Beam, I used my iOS app to connect it to Wifi but then paused any activity on my phone once it was connected. I then opened my Mac Desktop app and connected to the system and was able to run the update. 
I’m in. Thankfully that torture is over. Now to see how terrible the functionality of this app really is. 

same issue here.

I just changed router to netgear XR1000. Is it the reason?? I don’t know what to do...

I’m having the same problem.  The support is worthless.

Got message to update, resulted in endless loop saying owner needs to log in. Read this thread, went to a Mac desktop, downloaded Sonos app and problem solved. They should get the people who created to Mac OS app to do the iOS app, send you can’t do it on phone.