If you’re a Lumia Icon owner do not update to Lumia Denim, read this first and then make your decision.
On February 11, after a long time waiting, Microsoft gave the OK and began rolling out the Lumia Denim update to Lumia Icon Windows Phones. However, short after the release, users are reporting issues updating on hardware participating on the developer preview. Basically, after trying to install the update using the Over The Air (OTA) system, phones become unusable.
Perhaps the reason is because the Windows Phone was part of the dev preview program, but according to Microsoft’s Joe Belfiore, users should be able to update without the need of using the recovery tool to reflash and re-apply the new software. However, users are sharing images with the phone showing BSOD and rebooting the phone only shows the same screen.
Hey #Icon users… thanks for being patient! Denim is arriving today, but sit tight. You WON'T need to reset & use recovery tool to get it.
— Joe Belfiore (@joebelfiore) February 11, 2015
It’s worth noting that Lumia Icon handsets running stock Windows Phone 8 are updating fine, it’s simply those Windows Phone that where participating in the dev preview program.
I hope you’re reading this article before updating your phone. If you’re looking to upgrade anyway, be sure to backup your data, and make sure you have the recovery tool to fix the phone if something happens.
Source Neowin