Earlier today, we reported about the new Facebook Messenger Beta availability for the Windows 10 Mobile. Unfortunately, it is not available for all the regions and this made many users sad. Good news is that we found a way to install it on your phone for any region you belong to.
Go to settings>Time & Language>Region and change it to Germany. After selecting, restart your device and download FB Messenger Beta. It should download normally for you now. Once downloaded and installed, you can change your region to the desired one.
You can download new Facebook Messenger Beta from here