I would like to give you a background on Universal CRT this would help you in understanding as to why the system should be updated before installing vc_redist.x64.exe. A large portion of the C-runtime moved into the OS in Windows 10 (ucrtbase.dll) and is serviced just like any other OS DLL (e.g. kernel32.dll). It is no longer serviced by Visual Studio directly. MSU packages are the file type for Windows Updates.
In order to get the Windows 10 Universal CRT to earlier OSes, Windows Update packages were created to bring this OS component downlevel. KB2999226 brings the Windows 10 RTM Universal CRT to downlevel platforms (Windows Vista through Windows 8.1). KB3118401 brings Windows 10 November Update to the Universal CRT to downlevel platforms.
Windows XP (latest SP) is an exception here. Windows Servicing does not provide downlevel packages for that OS, so Visual Studio (Visual C++) provides a mechanism to install the UCRT into System32 via the VCRedist and MSMs.
1.The Windows Universal Runtime is included in the VC Redist exe package as it has dependency on the Windows Universal Runtime (KB2999226). Windows 10 is the only OS that ships the UCRT in-box. All prior OSes obtain the UCRT via Windows Update only. This applies to all Vista->8.1 and associated Server SKUs.
For Windows 7, 8, and 8.1 the Windows Universal Runtime must be installed via KB2999226. However it has a prerequisite update KB2919355 which contains updates that facilitate installing the KB2999226 package.
Why does KB2999226 not always install when the runtime is installed from the redistributable? What could prevent KB2999226 from installing as part of the runtime? The UCRT MSU included in the VCRedist is installed by making a call into the Windows Update service and the KB can fail to install based upon Windows Update service activity/state: 1) If the machine has not updated to the required servicing baseline, the UCRT MSU will be viewed as being “Not Applicable”. Ensure KB2919355 is installed. Also, there were known issues with KB2919355 so before this the following hotfix should be installed. KB2939087 KB2975061 2) If the Windows Update service is installing other updates when the VCRedist installs, you can either see long delays or errors indicating the machine is busy. a. This one can be resolved by waiting and trying again later (which may be why installing via Windows Update UI at a later time succeeds). 3) If the Windows Update service is in a non-ready state, you can see errors reflecting that. a. We recently investigated a failure with an error code indicating the WUSA service was shutting down.
To identify if the prerequisite KB2919355 is installed there are 2 options: Registry key: 64bit hive HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Component Based Servicing\Packages\Package_for_KB2919355~31bf3856ad364e35~amd64~~6.3.1.14 CurrentState = 112 32bit hive HKLM\SOFTWARE[WOW6432Node]Microsoft\Windows\CurrentVersion\Component Based Servicing\Packages\Package_for_KB2919355~31bf3856ad364e35~x86~~6.3.1.14 CurrentState = 112
Or check the file version of: C:\Windows\SysWOW64\wuaueng.dll C:\Windows\System32\wuaueng.dll 7.9.9600.17031 or later