Don’t Delete Windows Installer Folder From Your PC – Know Why


When I first started my career as an enterprise software packaging expert, I made my fair share of mistakes. One of the most dreadful mistakes I’ve made so far was deleting the windows installer folder. So, if you’re reading this article, you probably want to remove the massive windows installer folder but aren’t sure if it’s safe to do so.

The windows installer folder in C Drive is a secret system folder that can only be seen if the File Explorer is configured to reveal protected operating system files and hidden files. Depending on the number of programs installed on your computer, the Windows Installer folder may take up a few MBs to GBs of disc space. But should you delete it? The answer is NO!!!

Why Is The Windows Installer Folder Used?

Windows 10 caches installer data files and patch files for apps that use the Windows Installer Service in the windows installer folder. The size of the folder is determined by the amount of Windows Installer-enabled apps on your computer.

The installation folder is hidden by default by the operating system. It’s not difficult to find, and it’s not secured by any further security measures, such as assuming control of the folder. This is the folder that Windows Installer uses to cache all MSI, MST, and MSP programs.

It implies that Windows Installer initiates a caching process in the app/C: Windows Installer folder whenever you install an app or a patch on your computer.

Is It Safe To Delete Files From The Windows Installer Folder?

No. Files in the WindowsInstaller directory should not be deleted since they are necessary to repair, update, and remove the software. It is, nevertheless, safe to remove orphaned files.

Every application installed using Windows Installer fails to uninstall itself if the whole contents of the installer folder are deleted.

A program must know exactly what to remove from the system (files, registry) or what extra Custom Actions must be performed during uninstall before it can be deleted.

Even though an application is installed on the system and specific information is stored in the registry, the data mentioned earlier may only be retrieved from the cached MSI.

How To Delete The Unused Files From MSI And MSP?

Patch Cleaner is a tool that is mainly intended to remove unnecessary files from the Windows Installer folder. Simply start the program, and it will do a scan and display the findings in a window. It thinks that the files that are still in use should be kept, but the orphaned files should be deleted because they are no longer required by any installed software. Several Gigabytes of orphaned files might be found after the scan is complete.

If you have enough space on another device, relocating the files is preferable rather than deleting them directly. That way, if something goes wrong, you’ll still have a backup. To find a destination folder, click the Browse option. You can define an exclusion in the Settings to exclude MSI or MSP files associated with specified applications.

Read More: How To Uninstall Avast Secure Browser: 5 Basic Methods?

What Happens If You Delete Files From The Windows Installer Folder?

You can get an error if you delete files from the Windows installer folder and then try to update, repair, or uninstall applications whose installer files you deleted. Some apps may not be able to be entirely uninstalled due to the mistake.

Meanwhile, suppose you want to free up some disc space in Windows 10 by removing files from the WindowsInstaller directory. In that case, there are several other to free up disc space in Windows 10, and those ways are far safer than deleting the Windows installer folder.

What To Do If You Accidentally Delete The Windows Installer Folder?

You can attempt recaching the MSI/MSP or recaching the MSI and MST to fix, patch, or uninstall an application no longer cached in the installation folder. However, it will only work if the installer contains a transform file in the first place. 

Mostly this idea always fails because the program is detected as already being installed on the computer. Things tend to get a little more complicated when you utilize an administrative solution like SCCM or Intunes. Still, it may fix the problem you caused after deleting the Windows installer folder.

The Steps Are:

Step 1: Let’s start by making a basic MSI with an exe file, a registry, and a custom action that opens the exe file after the installation is finished. A cached MSI appears in the installer folder after the installation.

Step 2: Try to repair the program now. But, it fails when you try to fix it using msiexec /fus ProductCode after deleting the cached MSI from the installer folder and removing the source MSI.

Step 3: Therefore, you should click on the Cancel button since we assume you don’t have access to the source MSI.

Step 4: As previously indicated, re-caching the program also fails. So, what’s the next step?

Step 5: Let’s assume we discover the old MSI media and move it somewhere else, then remove it from there. Unfortunately, nothing of these options will work too.

Step 6: At this time, the only option to get rid of the program is to use the workaround we used for Recache MST recaching MST. It will likely solve the disaster you caused by deleting the Windows installer folder in the first place. 

Final Warning

The importance of not deleting or emptying the installation folder cannot be overstated. If you want to delete the MSI and MSP files, you don’t need to delete the Windows Installer Folder entirely. We have mentioned a few ways here to delete them, and we could remove the MSI using those techniques discussed above. Just keep in mind that it takes a long time to fix such a mistake, and it’s nearly impossible to succeed 100% of the time even if you follow our solutions. So, if you want to know anything else about this, ask us in the comment box below.

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