This is quite simple. My config ID is 146764 and my firmware is on 1030.6407.1308.0002. My Lumia 620 was bought from Amazon.com and I use it here in the United states but it is the international version from the United Kingdom. If you check the
Nokia update availability website you?ll see that, in my case, this is the device that?s used by 3UK, O2 and Virgin. The latter 2 are listed as COMING SOON (meaning, it's approved and being released to their servers) while 3UK is waiting for approval.
This is the reason why we (myself included) are getting this update "error" message. It's not an error per se: we can't access the update because it's being prepared into the servers as we speak. It could be 1h or a few days until it's available, but this "error" means that they're updating the servers and GDR2 should be available soon, at least to those 620s with the 1030.6407.1308.0002 version of the firmware.