Check your firewall settings:

https://support.sonos.com/en-us/article/configure-your-firewall-to-work-with-sonos

Thanks I've tried these steps and it gets the same error. Doesn't work still

I actually had my music library working (at last!) but after updating the Mac desktop app today now get the 1002 error message, and re-adding the library is failing despite the path being identical to what previously worked…...

Are you using the Sonos app on Windows to add the share?

​@MoPac yes its windows. 

I am using the same paths and settings that previously worked.

windows desktop > hardwired to ethernet switch > hardwired to router > full fibre

cheers Matt
 

I have found the solution to error 1002 sonos music library issue

the solution: (on windows at least)

select the my music folder, right click > properties

select > sharing tab, select> share

add name “sonos” the will add the name “sonos wireless hifi system” 

enable read/write if not already there. the path of you’re shared folder will also be visible

back to the sonos controller app (in windows) add music library, select the location/path and enter

the library was added as before the updates.

the software is very bad, the error feedback given to this problem from the app was unhelpful. I will actively discourage buying sonos to friends family and colleagues.