Unable to add Music Library on new Windows 11 PC

You’re the second person to report this today.  It looks like it’s cause by the latest Windows 11 update.  Not seen a fix for it yet but someone from Sonos might suggest how to resolve or raise a ticket for it.

But have you considered a Network Attached Storage Device (NAS)?   Far more efficient than leaving your PC on all the time as well as divorcing you from Microsoft's latest whim!  

Are you sure any of the ports you are forwarding aren't interfering with Sonos? 

I have no ports forwarded and mine works fine, I do use a SMB server, not Windows though.

I went the NAS route to avoid the constant Windows update related issues, much less frustrating.

As ​@bockersjv has stated, a NAS would be the best solution. 
 

A lot of users have had issues Sonos getting disconnected or simply not being able to connect to a shared folder on Macs and Windows PCs. With so many security updates being pushed out by both Microsoft and Apple, things will break. 
 

I have a Synology NAS where I store all my media. But you can choose any NAS that is available to you. I would stay away from WD MY Cloud devices though.

Thanks for the input. I won’t buy a NAS though since it has worked before on my PC, my PC is on most of the time (due to work, video games etc.) and the file sharing works fine and is accessible from other computers on the network.

Could it have something to do with the total size of the library? I have read something like there is a meta data file limit in Sonos.

​@Stanley_4 The ports should be fine. They are specified by Sonos in their official documentation:
https://support.sonos.com/en/article/configure-your-firewall-to-work-with-sonos

Got confused by your "forwarded" where Sonos says "open." 

Curiosity question, what firewall are you running that needed the added configuration?

Did you change the password on the NAS shared folder which you are adding to W11?

I had to change password of my NAS account due to a security issue.  Sonos was unable to connect to the libraries thereafter.  Removing the library from Sonos app worked, but they could not be re-added with the new password.  Reverting the password to the old password on the NAS allowed the libraries to be reattached.  The app gets one of the Sonos items in the system to do the connection to the NAS to create the music library.  During the add library process with the new password, Nas logs showed that connection was successfully made to the share with SMB3, but then three failed SMB1 accesses were recorded.  When the password was reverted, the share access was the only item logged.  I infer that the Sonos system devices retain a cached username/password combination for an SMB file share and that this is not removed when the library is removed.  If right, this needs to be sorted.

This may not help in your case, but might be found by others!

This is usually caused by Windows 11 security and sharing settings.

Make sure the music folders are shared using SMB 1.0/2.0, as Sonos does not support newer authentication methods.
On the Windows 11 PC, enable SMB 1.0/CIFS File Sharing Support in Windows Features.
Use a local Windows user account with a password, not a Microsoft account, and grant that user full access to the shared folders.
When adding the library in Sonos, enter the path using the PC name (for example \\PCNAME\Music) and log in with that local username and password.
Also confirm that password-protected sharing is enabled and the PC is not set to sleep or power down drives.

After changing these settings, restart the PC and Sonos app, then try adding the Music Library again.

Moderator edit: Likely AI-Generated and would be removed if not quoted below.

SMB v1 is only for Sonos S1 sharing. SMB v2 or higher is for Sonos S2 systems. 

Sorry to be frank, but your instructions are completely wrong.  S2 systems can only access SMB v2.0/3.0.  They aren’t compatible with SMB v1.0.

Moderator edit: [AI-generated post removed]