Problem 

When installing vc_redist.x64 on windows server 2012 R2,  got "0x80240017 - Unspecified error"



we open the log then we could find Error message:
Error 0x80240017 : Failed to execute MSU package.
we also know we could not excute KB2999226.msu from the log.



no luck, we excute KB2999226.msu (no matter it's from Package cache or microsoft download page),
we got the error message.
The update is not applicable to your computer




Problem Solving Steps

On Microsoft forums, we know we need to install KB2919355 before KB2999226.msu

Ensure KB2919355 is installed. Also, there were known issues with KB2919355  so before this the following hotfix should be installed.
KB2939087 KB2975061
We download KB2919355.msu from https://www.microsoft.com/en-US/download/details.aspx?id=42334 and excute it, we got the same error message : The update is not applicable to your computer




On Microsoft support site : https://support.microsoft.com/en-us/kb/2919355
We could find hotfix:
Update for Windows Server 2012 R2 (KB2939087)

After install Hotfix, we can excute KB2919355.msu.
Restart the computer, then we can also install KB2999226 and vc_redist.x64.


Reference

1.https://social.msdn.microsoft.com/Forums/vstudio/zh-TW/64baed8c-b00c-40d5-b19a-99b26a11516e/visual-c-redistributable-for-visual-studio-2015-rc-fails-on-windows-server-2012?forum=vssetup
2.https://social.msdn.microsoft.com/Forums/vstudio/zh-TW/64baed8c-b00c-40d5-b19a-99b26a11516e/visual-c-redistributable-for-visual-studio-2015-rc-fails-on-windows-server-2012?forum=vssetup