Amazon U.K. and Amazon France halt sales of the Microsoft Lumia 950 XL
Amazon Germany pulled the phone from its site recently, and Carphone Warehouse had to delay its pre-order period for the handset. There is some speculation that units are being sent back to Microsoft to be updated to the latest OS and firmware, which will resolve some issues that the phone is having.
You can wait for the latest OS and firmware versions to be sent to your Lumia 950 XL OTA, or you can use the Windows Device Recovery Tool to flash the latest versions on your phone. The latest firmware brings some improvements including the ability of the phone to download and install international keyboards. The update will also bring improvements in Windows Hello, which allows the iris scanner to unlock your handset with just a glance on your part, and increases battery life.
The update also makes the Glance screen better, and improves the "Hey Cortana" voice activation for the virtual assistant. If the sales halt was done merely to update Lumia 950 XL stock, it shouldn't be terribly long before the phone is once again available.
source: AmazonUK via WMPoweruser, WindowsCentral