We have added a privacy page to the Windows 10 Mobile OOBE and upgrade experiences that allows you to quickly and effectively make common privacy changes while setting up the device. However, Insiders have reported that their device would crash or reboot shortly after unlocking their device for the first time after the upgrade if their device did not have a password configured to unlock the device. After updating to Build 15207, you will see this privacy page one more time – but should no longer experience a crash or reboot.
Thanks to the Insiders who reported this issue and helping us fix issues quickly like this one!
(content above was copied/pasted directly from the blog)