iTunes Match warning,"This device is already associated with an apple id" .How do I solve?

There is no way to overcome this. You can only associate one Apple ID at a time iTunes Store: Associating a device or computer to your Apple ID

Jim

I suddenly have this same issue (iPhone) too, except that this is the only Apple ID that has ever been associated with this iPhone (unless Apple sold it refurbished without mentioning.

The only thing I can think of is that during the update to 8.4 the iPhone crashed, so - with Apple guiding us - and we had to erase and restore the settings. But I can't see how this is it because (1) there has still only ever been the one ID; (2) the day count on the message doesnt match up to the date of the reset; and (3) it didn't start happening until two weeks after the reset.

Any guidance is much appreciated as it kind of stinks to have purchased sings that apple won't let you play.

IPhone 5c, iOS 8.4

Hi,

I suggest that you contact Apple support Contact Apple for support and service - Apple Support

Jim