Microsoft has now posted a changelog of this update, and it looks to a rather interesting one with many improvements.

Over the last 24 hours, we have seen reports from many users that a new firmware update was going out. The update is under the guise MICROSOFTMDG update and while the OS remains the same the firmware does change from 01078.00017.15452.xxxx to 01078.00027.15506.xxxx .

New firmware update for Lumia 950/950 XL: 01078.00027.15506.020xx

Stability and performance improvements.

Improvements for SD memory card support.

Improvements for automatic display brightness settings.

Fix for a camera problem that was causing noisy images in low-light conditions for some users.

Fix for a 4K video problem that was causing stripes to show up while playing back recorded videos for some users.

We should caution that the update appears to be rolling out for those in Europe first with many getting the update starting yesterday. However, none of our phones here in the US, including our AT&T Lumia 950 and unlocked Lumia 950 XL are seeing the update just yet. Microsoft says the update is rolling out gradually:

"The update should be already available for many of the users and rollouts will continue gradually. Availability of the update may depend on your network service provider."

That last line is a little concerning for those on AT&T specifically. On the other hand, we are less than 24 hours into this process, and even our unlocked device is not seeing the update so no conclusions can yet be drawn.

Regardless, you can see if you phone has the update by going into Settings > Update & security > Phone update > Check for updates to see if it is live. If it is, you should see a MICROSOFTMDG update waiting.

We'll follow up this article with another when it hits the US and other territories.

Anyone already have the update? How has your experience been? Let us know in comments!

Source: Microsoft; Thanks, Henning S, Pär P,. and Victor V., for the tips!