Sonos unable to play music through Plex app or when requested verbally through Alexa

Server Version#: 4.18.1
Player Version#: n/a

So many devices and services involved here I wasn’t sure which category to list it under.

I have a Sonos One linked to Plex (PMS running on Windows 10) and both devices are ethernet connected. Music is stored on my NAS, which is also ethernet connected.

Inside the Sonos app (Android), I can browse my Plex music and play it through the Sonos One with no issues.

Inside the Plex Android app, I can play music fine through my phone, but when I try to cast it to the Sonos One, a receive the error shown below:

When using Alexa to request Plex music on the Sonos One (which is set up with Alexa), I receive the following error message from the Sonos app (assuming it’s open on my phone at the time):

A song which plays without problems through the Sonos app will not play when chosen through the Plex app or when requested through Alexa. File types I have tried are m4a and mp3.

Would appreciate any help solving this puzzle.

Experiencing the same errors here but some additional strange behaviours
Server Version 1.18.4.2171 new installatation on Windows 10
Lastest Plex App for Android
Lifetime Pass
Sonos One Gen 2

Sonos App is able to play from Plex
Cannot cast from Android Plex app (player symbol goes orange but then get the same error)
Alexa is able to play Prime Music (and can control Sonos for next track/ stop etc)

  1. I already have an Echo device and “Alexa ask Plex to play xyz” works 100% on the Echo for all tracks/.albums tried

  2. My collection is all mp3 and a small number of albums play 100% of the time without issue on the Sonos
    I have used Mediainfo, Plex info etc to try and see if there is any difference between those that play and the rest
    The Windows Sonos App shows the various error messages that come up when a track is failing - Unable to play ‘Plex’ - the file is in an unsupported format
    -Unable to play 'start?X-Plex … ’ the file is in an unsupported format
    This also shows the correct song/artist and albumart but when the request is “Alexa ask Plex” the album is shown as Plex even when playing correctly

Using the web browser on Chrome then I can see the Now playing
Have not seen any differenvce between the failing and the working
This screenshot shows the failing streaming to the Sonos on left and the working streaming to Echo on right

So there are two clear failings -
(a) with PlexPass the cast to Sonos should work
(b) If Alexa is able to play plex on the echo then this shows the remote access etc is setup correctly and should work.

It’s suspicious that the Sonos app is showing parts of the play URL e.g. start?X-Plex as though it was the filename

I’ll try and get some clean logs with just a succeeding and failing track

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Seems like you know your way round Plex a little better than me - if it would be useful for troubleshooting for me to also provide ‘clean logs’, can you explain what those are and how I can produce them.

Sorry for the delay

All I meant by “clean log” was that I would stop the Plex Server - most easily done by right clicking the Plex icon in the Windows system tray and selecting Exit
I would then restart the server, wait 1 minute and then start whichever player I was investigating - this just made it easier to find the entries in the log file)
Then the log files can be obtained in 1 single zip file using the Troubleshooting section of the Server settings - see https://support.plex.tv/articles/200250417-plex-media-server-log-files/

I’ve created a new post as I also tried capturing all the various packets flowing between the server and the Sonos One to work out why some files played correctly when requested via Alexa on the Sonos. I found that Alexa-Plex-Sonos worked OK if the files had not been “analysed”. If I analysed the files (which then creates a profile of the loudness) then I get the same error as you see (the Unable to play 'start?X-Plex-Token… message).

You can tell if your files have been analysed by navigating in the web browser to a track and selecting the three dots and “Get Info” This shows a file that had been analysed

To unanalyse you need to remove the media from the library, (either remove the folders from Plex or as test just delete the files - assuming they are backed up) recan the library (and then restart the server to be on the safe side). Add the media back, rescan and then try again with Alexa.

If you have just requested a failed file then you might need to request more than one working file.

I have also disabled Plex for reanalysing the files Settings->Server->Library and then scroll down to Analyse audio files and set to Never. (default setting is as scheduled task )

It would be good to know if your files had been already analsysed and if newly added media works correctly with Alexa on the Sonos One

(This has made no difference to trying to cast Plex from Android to Sonos but the Sonos App does that job OK)

@bubbabr a fix went out today that should fix your casting issue.

Updated PMS, but issues unresolved.

Similar ‘X-Plex-token…’ error message when requesting Plex music through Alexa. Likewise, songs cast from within Plex Android still don’t play on Sonos (though it appears no error message now displays inside app).

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Thats a plus one. I am having this problem as well.
Playing music has become a real issue.
Plays ok from plex when started from sonos app.
when started from alexa voice app using plex command…major problems.
Sonos shows File unable to play - unsupported format whilst on plex dashboard at the same time it is showing as playing but no sound from sonos One. Also there is no control on the dashboard by hovering ie cant stop. Also if a second request is made via Alexa it displays on dashboard as a second running song with no sound - both with orange bars moving and showing song progress.
Occasionally will play from alexa( - no apparent reason it works sometimes and others not )but plex plays one or two songs from the requested artist and then stops playing.
This is a recent issue for me over last 3 or 4 months as around June July 19 My Alexa/Plex/Sonos system sarted to work perfectly…now glitched again.
All my music collection is in compatible format. Using all updated software on Alexa, Sonos and PlexMS.

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By The Way
Meant to say the fix mentioned above was installed and didnt

Sorry just getting the hang of this screenshot thing.
The Left item is the Alexa request - showing as "Unable to play - 'start?XPlex token x - no sound unable to stop- orange bar progressing. Bar progresses to end and then flips back to middle of song on endless loop
The right is the same song started from my Sonos app from Plex collection - playing perfectly
Neither Respond to the hover to stop
Also the L hand song is showing time played as 4.33: 2.35

This was the problem I had.
I solved it (as described here ) by removing the analysis that Plex does overnight (loudness analysis)

Test it out by adding some new music (or deleting say one artist, updating and then restoring)
Just make sure your server settings are set to never analyse

I now can play all my plex songs by voice request on the Sonos One. (I had to remove and then add back all music so this did take a whiel for all the metadata etc to be retrived)

2 Likes

Thanks astronaut - tried it with a sample album and seems to have worked. Now begins the long process of re-adding all my music!

From what I understand, there’s no way to submit a bug report to Plex developers right? You just have to attach a log file to a forum post and hope it gets noticed?

For anyone else looking, go to Settings > Library > and set ‘Analyze audio tracks for loudness’ to Never.

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Yes Second that astronaut - Job well done!!!
Saw your post last time I was here and deleted library and re added my whole library and set analyze to NEVER- took me days BUT seems to have fixed the problem. Cant thank you enough -

Oh Dear
Solved that problem and now Alexasonoplex has reverted to playing one song only no matter what the request ie track, artist , album. i thought Alexasonoplex had fixed that glitch months back. Now its back.
( Shakes head sadly - big sigh …) In the last 2 years I have had Alexasonoplex actually functioning properly for about a month…the glitches are never ending. I cant find where this is happening - any thoughts. sonos plays the song but it doesnt appear on the plex dashboard
Really regret the plex pass purchase

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Sigh. I’m clearly not the only one. I have gone months (years?) without plex/Sonos issues but ever since trying to integrate with Alexa everything has gone to pieces.

Files constantly say “unknown format” (they’re mp3 FFS!). Plex and Alexa and Sonos is totally non functional to me

I Feel for you Matt
Its now May and this problem still persists despite now being noted multiple times.
To add insult to injury Alexosonoplex is now stuffing up my music play back.
Now Spotify is playing one song and then stopping. Obviously this isnt Plex related but as you so eloquently put it …FFS.
Cant these three bits of equipment geeks talk to each other and solve the problem.
They are only to happy to sell the equipment with glowing promises of seamless music and video access at the owners command.
The grubby reality is - they dont work and once the companies have your money , you are on your own baby!
There is no way of accessing help other than emails that either arent answered or referral to FAQ sites that are absolutely no help.
Really, really REALLY regret wasting money on a plex pass.

Sigh,
As of last night now no music from plex at all
It opens plex says playing requested music but no sound and nothing shows as playing on the dash board. Remote access is enabled. Everything looks normal
Will SOMEBODY from plex please fix this .
I cant seem to conatact plex at all. No web desk, no phone , no email…

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