To fix it I had to remove the Sonos Alexa skill and add it back again. It kept all my devices room setup it seems.

Open the Alexa app tap on More, tap on Skills & Games, scroll to the bottom and tap on Your Skills, tap on Sonos, tap on disable skill.

Then just add it back. You will need to link your Sonos account again.

Problem resolved: First I removed Alexa from sonos as a voice service, then disabled the sonos skill in Alexa. Then re added Alexa as voice service and re enabled the sonos Alexa skill (which relinked to sonos). That got it working again. 

I followed this and it fixed my issue, this works! Thank you. I joined just to confirm this works.

Hey, just wanted to say thank you, this solve the problem for me!

I had this today, a quick fix was to play a song on Spotify within the the Sonos app (not Spotify app). Then when I asked Alexa to play Spotify I could use the Spotify app as normal

Same here, I came back from a short trip and found Alexa responding “this device is offline”, I then tried everything listed here, also a factory reset and setting up everything again, but cannot get Alexa set up anymore. On the Amazon app, it can't find the Era 100 device; on the Sonos app, when I get to the "Signing in to Amazon...” dialog, it hangs there forever. Infuriating...

 

The same happening here as of the last couple of days. Worked fine for years before this. Tried all the ideas above but nothing works. My Alexa app just says all my speakers are offline. Thoroughly sick of it. 

Check that the Sonos ‘Skill’ is linked to the correct Sonos Household/System in the Amazon Alexa App - best thing to do is remove the skill and setup the sharing agreement again as you re-link it to the correct Sonos Household.

Thanks for the fix! I had the same issue, and removing and re-adding the Sonos skill resolved it for me as well. It's great to know that this method keeps your device setup intact. Appreciate the clear steps!

Also having the same issue on my Sonos beam. No problem connecting my Sonos move with Alexa, but the beam can’t get things working. 

What does the device list show in the Alexa App settings?

Check the properties of the Beam - in my case, I have a Beam called ‘Kitchen’ with an Alexa component called ‘Sonos Kitchen Alexa’ - see attached screenshot - it shows as being ‘online’ and is working fine here.

Also check the device is uniquely named in the device list and is not duplicated, or named the same as another device.

I would also ensure it has a different name to any ‘Alexa enabled group’.

The same happening here as of the last couple of days. Worked fine for years before this. Tried all the ideas above but nothing works. My Alexa app just says all my speakers are offline. Thoroughly sick of it. 
 

My understanding is that everything is related to the Sonos app and the Alexa voice assistant setup within that app, i.e. I don’t think this is connected to the Alexa App. 

I had exactly the same issue with my Sonos Arc and Alexa. What worked for me was to change my preferred music streaming service from Spotify to Amazon Music (I have accounts for both), within the Sonos app. When I asked Alexa to play music it would then connect to Amazon Music and play without any issue. I then swapped back to Spotify and it worked. 

Hopefully, this will help someone. 

 This solved the problem for me. I delinked everything and disabled the Sonos skill in Alexa app then re-added which didn’t fix it. But then I played a song from spotify in the sonos app as per this post and it all came back to life. 

Wow, this took a long time for me to resolve. Firstly, I went onto the Amazon website and I went into my account. Got a list of all my devices and deregistered and removed everything I could possibly find. Then I did a factory reset on my Sonos speaker. Then I set the speaker up from scratch I added Spotify as the music service and I added Alexa as the voice assistant and then I went onto the Alexa app on my phone and I added the Sonos skill. Initially, this didn’t work when I tried to ask Alexa to play music out of my speaker, So I went into the Sonos app and I used it to control the speaker and play music then I paused it then I went into the Spotify app and I used it to play music out of my speaker then I paused it. Then finally, I went back to my Sonos speaker and I asked Alexa to play Spotify music and it worked straight away. I can’t be certain if this is an exact order, but I think the fundamental things to do are to remove every possible trace of devices on the Amazon website deregister everything you have and start again with a factory reset. 

 Is your TV a Sony?  My two Sony TVs do this now, but the light on the Arc & Beam 2 do not turn green.  When I turn on the TV there is no sound, but the LED is white.  When I touch volume up a mute symbol shows on the TV.  I only need to touch volume up on the remote once at which point the volume returns to the last used setting.  I do NOT have to keep touching volume up to get the last used volume.

 What does yours do at this point?  Is the behavior the same as mine?

really frustrating and a terrible user experience, Sonos. I tried disabling the Sonos skill in Alexa and then removing the service in Sonos - doidn;t work. Then disbaling Alexa as a voice assistant - didn’t work.

What WORKED: disabling all these things AND then disabling the sonos skill in the Alexa app AND changing the name of the room (and deleting all old rooms).

What a faff. Sonos Ux and Ui sucks!

Wow, this thread shows continued epic fail of Sonos.

All above remediations tried, some with temporary and limited success.  My current involves the message shown above in screenshot (“Device is offline...”).  So then if you deregister the device it stops showing as being offline, but does not show any registration information, and doesn’t work via Alexa.

So now if I try and make the Sonos the default device for my room, I get this message:

 

Same issue here

just happened today!

any tips/advice?

I tried removing skill, de register and reboots 

any other ideas? Anything to do with the network maybe? I have a unifi network. 

This has started happening to me now, so far I’ve tried disabling and re-enabling the Sonos Skill in the Alexa app, and unlinking and relinking my Spotify Skill - both yield the same “Sorry, that device is offline” :(

Yes, this “works” for me .. but it is annoying to have to do this every few days to get Alexa voice control + Spotify + Sonos working again. 

Knock on wood, the problem has not reoccurred for me. Now my only annoyance is that every time I turn on the TV, my arc starts at volume 0. It doesn't remember whatever the volume was set at when I used it previously. I guess it's always something... 

Having the same issues. 
 

above is only a temp fix as next time (different day) the same thing happens. Sick of having to re register my Sonos arc to get Alexa to play Spotify..

any tech support answers? 

I am now getting this problem and have tried the skill removal and installation with no joy…..

Spent an hour on customer service chat, tried various versions of resetting stuff, nothing worked… was finally asked to call in to tech support, but getting in touch with them is horribly difficult, I'm on hold now, "wait time is 70 minutes” I think I've had enough of Sonos and it's time to purchase new speakers...

Looks like this Basic advice simply does not work for most of us.