Microsoft's official statement
"We are currently investigating the issue. We have paused delivery of the update to customers using the Preview for Developers, and will resume once a fix is in place. Customers whose phones have been affected should use the Nokia Software Recovery Tool to return your Lumia to a normal commercial software state before downloading the Lumia Cyan update."
The problem only effects users who downloaded the 8.1 developer preview , normal users will receive the update without any problem what-so-ever
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