Under the Sonos One settings under “Voice”, did you set up Alexa under “Add a Voice Assistant”?

Yes. I get an error saying “there was a problem adding Alexa” or something like that and two options. Try again or use another account 

Try rebooting your phone and unplugging the One from power for about a minute. Then try setting up Alexa again.

I’ve already unplugged the device and started all over again. It had no effect. I’ll try rebooting my iPad. I haven’t done that yet. I seem to be stuck in some sort of loop. I can’t add a voice assistant and when I try to enable the Sonos skill on the Alexa app to add the voice assistant, it tells me I have to connect the device to my Sonos account, but I’ve already done that. Next stop is to hit it with something large and heavy, which seems like the most satisfying option right now.

Can you also check your location in your profile on www.sonos.com and your device settings for your Sonos device within the Alexa App.

Thanks for that. Yes I think location could be an issue, but I can’t pair the device with Alexa app so I can’t do what you’re suggesting 

Did you check your profile on www.sonos.com?

Are you signing into the same Amazon account when trying to link your Sonos skill as you have logged into on your mobile device?

What country are you in and registered on your Amazon account??

Note: Your profile on sonos.com can be different to that of your profile on the community. :)

Thanks. I will check that. I’m in the UK. The problem occurs when try to add a voice assistant on Sonos. I am guided to the Amazon log in page and that is when I get the error message “there is a problem connecting to Alexa” I tried to get round it by enabling the Sonos skill in the Alexa app but I then get another message telling me to connect the device to my Sonos account, but I’ve already done that. I can’t see a way round it

Okay.  Is the device working correctly from the Sonos App?

If Yes and your Sonos profile address is correct, then please logout of all Amazon related apps on your device and power down your Sonos Device for 2-3 mins.  Then open the Alexa App and add the Sonos skill - let us know how that works.

Roger that. Yes the device works with the Sonos and Spotify apps. It’s just the voice assistant that’s playing up. Can I just check what I’m looking for in the Sonos profile? Do I have to make sure it shows my location as the UK? I will follow all the steps you have suggested. Thanks for helping out. I appreciate it

Yep.

Before I do this, can I just ask you one more question? I have a Spotify family premium subscription so there are four of us with our own Spotify accounts within the one subscription. Do I need to enable Alexa voice recognition for each of us or will it recognise multiple voices so I only need to enable it once (if you see what I mean)

The linking of Sonos and Alexa is different from anything to do with Spotify. Have you added all four accounts to Sonos within the Sonos App?

I didn’t know you had to do that. I didn’t realise you needed a Sonos account for every Spotify account. I will certainly do that. But what about Alexa? Do I need to set up a voice assistant for each of the four accounts? I think I need to remove all of the apps and start from scratch one person at a time

Please see this article for adding multiple accounts from the same music service: Using multiple accounts for the same music service | Sonos

Voice control is more difficult as the relationship between a Sonos Account and an Amazon Account must be 1:1.  I haven’t tried this but please see the following steps within Alexa:

To add additional accounts, you'll need to login to alexa.amazon.com and head to Settings > Account > Household Profile. You can jump between them simply by saying "Alexa, switch profile".

This Spotify article may also help:

Solved: FAMILY AND ECHO ALEXA - The Spotify Community

Thanks both of you. This is all really helpful. I don’t think the voice control is important enough to set up separate accounts and profiles. My wife is the only one who is likely to use it. I’ve lost sight of the fact that the main problem is I can’t connect the device to Alexa. I need to look at those tips that were posted earlier and figure out how to fix it

I’m confused now! If you don’t want voice control why do you need to connect to Alexa?  Are you mixing up a Spotify and Alexa issue?

Sorry for the confusion. I will connect one of us to Alexa so that the Sonos Alexa connection is 1:1. The rest of us can do without it. Then all I have to do is figure out why the speaker won’t connect to Alexa. 

I just wanted to say thanks to everyone for helping me out. I managed to figure it out using various bits and pieces of this thread and it is working perfectly now