Where Is the Windows Installer Cache Folder?
Windows Installer cache folder with baseline MSIs, and why deleting it breaks uninstalls.
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C:\Windows\Installer caches a stripped baseline copy of every MSI based install on the machine. Uninstall, repair and modify operations all read back from these cached packages, which is why the folder only grows and never shrinks on its own.
The files carry random hex names rather than product names, hiding which entry belongs to what. That opacity tempts deletion during disk crunches, and it breaks uninstallers permanently when acted on. Treat the folder as system owned: measure it, work around it, never prune it by hand.
Where Windows Installer stores this, by platform
C:\Windows\Installer
Hidden system folder requiring admin rights to browse. Cached packages use random hex names, so identify entries through WMI or the registry rather than filenames. Patch cleanup belongs to Disk Cleanup, not Explorer.
Frequently asked questions
can i delete files in windows installer folder
Do not. The cached MSIs are the only copies Windows has for repair, modify and uninstall operations. Deleting them orphans installed programs that can then never cleanly remove themselves. Free space anywhere else instead.
how do i clean orphaned installer patches
Yes, with the msizap style removal tools only as a last resort for already broken entries. Patch files clean up through Disk Cleanup's update option instead. Manual deletion inside this folder is never the supported path.
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