Windows Installer Cache
The Windows Installer folder is a hidden system folder situated in C:\Windows\Installer. To see it, you have to through Folder Options, uncheck the Hide protected operating system files option. If you open the folder you will see a lot of Installer files, and folders containing more Installer files. Whenever you install a program using the Windows Installer, a copy of changed system information is placed in this folder. The folder contains the saved copies of the installed updates that are applied by the Installer. This information is required if you decide to uninstall the program. Most of the time, it won’t be complete files – it could just be the size of the triggering MSI. If you delete the particular folder or its contents, you may not be able to uninstall or repair or even update the program using the Windows Installer. You may at some point in time, face a situation where you find that your system drive is running out of space, and this folder is occupying a lot of space. Read: What are Windows Installer Patch (.MSP) files?
Is it safe to delete the Windows Installer folder or its contents?
Well if you empty the folder, your system would still continue to operate normally. But as mentioned, should you at any point in time decide to uninstall/repair/update a program, you would not be able to do so! Therefore, you should not delete files from the Installer folder; at least not manually, as this folder is a cache for installation files and patches (MSP files), and removing these will not let you uninstall, update or repair programs. Furthermore, it may even prevent you from applying or removing updates, or patches to software. However, if you are really hard-pressed to create more space on your system drive, you may try and cut-paste its contents to another drive for safe-keeping. These files are unique and cannot be shared between machines. Read: How to clean up unused .MSI and .MSP Files from Windows Installer folder. Alternatively, you may try and clean out the Installer folder by downloading Windows Installer Cleanup Utility and then running the command: When you run this command, the installer & patch packages are enumerated. The unreferenced packages are considered to be safe to be deleted. The “g” option removes, for all users, any cached Windows Installer data files that have been orphaned. Msizap.exe is a command-line utility that removes either all Windows Installer information for a product or all products installed on a computer. However, products installed by the installer may fail to function after using Msizap, and it may and may move the machine to an inconsistent state. As a result, Microsoft has stopped support for the Windows Installer Clean Up utility. See this post to troubleshoot Missing Windows Installer Cache files. You may also like to read the following posts which talk about other Windows system folders:
