EC: 0xC004C003 - cannot activate windows after upgrading to x10547

After upgrading to 10547, getting EC: 0xC004C003

Anyone else getting this. Is there a specific product key I need for this build?

Thanks in advanced

I've had this a couple of times (works for a bit and then loses activation). Best is to restore back to your previous activated build and upgrade again if running slmgr /ato doesn't work.

You don't need a key for 10547 or any recent build (and nor is there one).