Late on Friday Microsoft added a note to their blog post that announced last weeks release of Windows 10 Mobile Build 14977 for Redstone 2 and informed Windows Insiders that PC builds would be on hold temporarily while the Windows team implements the new Unified Update Platform or UUP.
UUP is a new technology that Microsoft announced in early November that will change the Windows Update delivery mechanisms and process in Windows 10 for both PCs and Mobile devices.
In fact, UUP has already been turned on for the Windows 10 Mobile Redstone 2 builds for a few weeks now and you can see and feel the speed improvements that this new technology is capable of providing.
So what is UUP?
According to Microsoft's Bill Karagounis, the Director of Program Management for the Windows Insider Program and OS Fundamentals, this new process will enable differential downloads to all devices that run Windows 10. Some of you might be familiar with the term delta download which almost means the same basic thing. When in use UUP and differential downloads will only deliver the bits that need to be updated on a particular device and not everything in one huge bundle.
In the past update might include files that were not changed from the previous updates and so the size of these downloads were larger than they needed to be and that would waste bandwidth.
Once UUP is fully implemented it is expected that download sizes for major updates to Windows 10, for instance the November Updates and Anniversary Update, could be reduced by 35% overall.
By incorporating UUP into the Redstone 2 builds that are pushed out to Windows Insiders, this bandwidth savings will be seen immediately and allows Microsoft to test it on a larger scale with Insiders just as they do other Windows 10 features.
One side effect of this new process is that full ESD copies of each update will not be downloaded to systems during these build to build updates to Insiders. That means the popular process of converting these Fast Ring ESD files into ISOs may become a thing of the past. Since Microsoft only releases ISOs once a build has been designated for the Windows Insider Slow Ring that means official ISOs will be few and far between.
To give you an example about how rare those Slow Ring and subsequent ISO releases are for Insiders only two builds (14931 & 14965) out of 13 total Redstone 2 builds have made their way to downloadable ISOs.
The conversion of ESD files to ISOs is not a supported process but it can be handy to start up a new machine on the Windows Insider Program instead of waiting 2 or 3 days for a device to be provisioned and then get the next Fast Ring release. I have used it a few times for that very purpose but if you are on a machine already running in the Fast Ring and want a clean experience after upgrading to a new Fast Ring build the Reset this PC process can deliver that as well.
Last week was a good time to call this pause on new PC builds as Microsoft ended up having a blocking bug in PC build 14977 which could break installed apps after the update. I suspect we will see the first PC build that supports UUP either late this week or sometime next week but keep in mind they will use the same ring promotion criteria to decide when that first UUP related build is ready so there is no guarantee when we will see it on our test systems.