Windows Universal Platform developers can see an update of the platform NuGet package. The version 5.2.2 was updated to 5.3.0. However, this update causes more issues than it actually solves. I recommend to halt the update and wait for at least one month.
The first problem is that this package requires an update to Visual Studio 2017 which is not released yet.
The Microsoft.Net.Native.Compiler package, included in Microsoft.NETCore.UniversalWindowsPlatform 5.3 and later, is only supported in Visual Studio 2017 and later. You can downgrade the version of the Microsoft.NETCore.UniversalWindowsPlatorm NuGet package to 5.2. or earlier for Visual Studio 2015.
The second problem is that Windows Dev Center rejects applications which are using the latest package.
This submission failed with error code(s) 1201.
The package is evidently not ready for production usage and should be marked is a prerelease. Unfortunately, it isn’t. Every Visual Studio should be carefully planned because every project depends on it. Specifically, projects depend on SDKs which depends on a specific Visual Studio version. For example, a project developed for Windows Phone 7.5 requires a Windows Phone 7.1 SDK which is not compatible with both Windows 10 and Visual Studio 2015, which are necessary for the development of UWP apps. Someone could argue that Windows Phone Silverlight app should be definitively updated to newer platform. That’s true, but it has a financial impact. Creating a virtual machine with legacy environment is usually less expensive. Just be sure that virtualization technology of your choice is compatible with Hyper-V, because Windows Phone emulators requires Hyper-V to be enabled.
The 5.3.0 version of UniversalWindowsPlatform package a is part of wider update which include Visual Studio 2017 and .NET Native 1.6 (the 5.2.0 version is based on the .NET Native 1.4). You should move to this version after migration to Visual Studio 2017 and after an announcement that the Windows Dev Center allows a submission of an apps based on .NET Native 1.6.