I am trying to make some space on a small C: drive and a search for large files has turned up two that I do not understand and cannot find a good description.


Does anyone know what these files are? There are over 200 MB in size for both of them. I would love to be able to recover that space, but I am afraid that they are needed.

Actually, I would hope that Windows is not using that much space for no reason.

  • Dumb huh? Where does Microsoft get the idea that wasting space by keeping unnecessary setup files (especially in the OS volume instead of the temp directory) is a good idea? ◔_◔ – Synetech Mar 31 '13 at 14:14

This page on Go 4 Answers implies that it's just a zip file:

6) Find the file netfx_Core.mzz and rename it with netfx_Core.zip and open with extractor

So if that's true and the fact they are in a folder called "SetupCache" implies that these are just the data files for the .net 4.0 installation.

If the installation is done and working then you should be safe to delete them. I'd either move them to another (larger) partition or back them up first just to be safe in case something still references them. In fact back up the entire contents of that folder before deleting.

  • Thank you both for the information. Unfortunately, I lack the rep to vote you up. But did mark as answer. – Jim Reineri Sep 28 '10 at 17:11
  • @Jim - That's OK. – ChrisF Sep 28 '10 at 20:21

These are indeed just data files for the client and extended .net frameworks - but just remember that you cannot remove or update the framework without these files being in place, so if you do move them bear in mind you may need to move them back when the framework gets updates.


The following webpage gave the decisive answer.

There´s 2 setup.exe files within the SetupCache-Folder, and if you are ever going to repair or remove .Net-Framework, it´s obvious, that the big .mzz installation-files (take a look inside with 7zip) will be needed.

Sample for usage:

C:\Windows\Microsoft.NET\Framework\v4.0.30319\SetupCache\Extended\Setup.exe /repair /x86 /parameterfolder Extended

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