Updating to s2 - error 9

I’ve got a system made up of four play:1 and two play :3.

Am trying to update to s2 so I can add a mini sub. But the update won’t work. Doing it from s2, it hangs and gives me an “error 9”.

I’ve tried factory reset on everything, downgrading everything back to s1 in the s2 app and then reinstalling it as a fresh system. But while the play:1 lot will all move over to s2 just fine, the play:3s always fail to update. Also an “error 9”.

I’ve spoken to Sonos and they say this is a temporary issue that they are working on. But it seems frankly unlikely that the one time I’m trying to do this is also the one time it has stopped working. Does anybody else have similar experiences?