Can't update to latest WM10 build on 640XL - help

[Ryujingt3]

I want to upgrade to the latest WM10 build. I download the update after enabling Windows Insider in Fast Ring.

Update is downloaded and installed. Phone restarts and displays the gears but it also displays an SD card and an x icon. It then restarts and says update failed due to SD card.

How do I fix this? Do I remove my SD card first? Should I hard rest 8.1 and update that way?

Thanks.

Ian