I too have just had issues trying to install VS2015, and solved the issue I was having. Took a morning at work to solve (this was actually something I was doing for work, not related to games). During installation (community for me, but enterprise was exhibiting the exact same issue), the installer writes logs to %TEMP% (ie c:/users/XXXX/appdata/temp), there’s a log for each component, look for logs to the components that failed to install, this should help you diagnose the problem for your situation. Below I outlined what I did to solve my problem, hopefully its the same for you:
TL;DR: Make sure .vsix files are associated with the new VSIXInstaller.exe in your failed installation folder.
For me TeamExplorer, nuget packager manager, etc… were failing to install. All of these failing packages are actually just Visual Studio extensions (.vsix files). It was failing to run the installer for these files. I think my issue came from it trying to use the incorrect .vsix installer (I have VS2012 already installed), the vsix installer itself dumps a log to the same location, it will be more descriptive, from this I derived that it essentially requires the new vsix installer (VSIXInstaller.exe) in c:\Program files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\ to run.
So to confirm sanity I extracted the .vsix for TeamExplorer from the .cab file, you can hunt this down in the package cache (C:\ProgramData\Package Cache) or an .iso installation, tried to install it (just double-click as it should be associated with an installer already possibly, if not just apply the solution anyway), and I received the same error message. Cool a repro case!
The solution is, open the properties of the file and change what that file type opens with to the vsix installer in the partially installed VS2015 IDE folder. Run the installation manually for it again and it should succeed (if not then look at logs again maybe its something different). I then re-launched the normal VS2015 installation process again, waited and great success!
Best of luck on this frustration.
Note: appdata and ProgramData are hidden folders.
Note2: I exhausted my weekly quota of swearing at the screen on this one, installers really need to be a bit more informative about how they’re failing, not just tell you to contact your vendor…
Note3: The logs it produces are super handy at finding the problems, albeit verbose as hell, search for “error” to make life easier, linux people would tell you to grep…