After Windows 11 clean installation from Windows 10, the unit C:\ still filled with lots of old files and folders. Don’t know why.

Understanding Why Your C:\ Drive is Still Filled With Old Files After Windows 11 Installation

After performing a clean installation of Windows 11 (W11) from Windows 10 (W10), many users have noticed that their C:\ drive is still cluttered with a multitude of old files and folders. This situation can be puzzling and may lead to questions about the integrity of the installation process and the overall management of disk space.

First and foremost, it’s important to clarify what is meant by a “clean installation.” In theory, this procedure should involve wiping the system drive and installing the new operating system. However, there are instances where remnants from the previous operating system linger, leading to the apparent presence of old files and folders. Here are a few common explanations for why this happens:

1. Temporary Files and Windows.old Folder

After upgrading to a new version of Windows, previous installations are often placed in a folder called Windows.old. This folder serves as a backup, allowing users to revert back to the previous version if they encounter problems with the new installation. However, if you performed a clean installation but did not wipe the drive beforehand, remnants such as this folder can remain. The Windows.old folder can consume significant disk space, sometimes several gigabytes, depending on the amount of data from the previous installation.

2. User Data and Program Files

In some cases, users may opt to keep their personal files or data on the same drive. If your previous installation had user documents, downloaded files, or even applications installed on the C:\ drive, those files will remain post-installation, contributing to the clutter. During the reinstall process, unless you explicitly choose to format your drive, all user data gets carried over—leading to an overflow of old content.

3. Temporary Internet Files

When you install or upgrade an operating system, your device may still retain temporary internet files, installation logs, or downloaded updates. Such files, while not crucial for current system functions, can consume space and appear as remnants from the previous installation.

4. Incorrect Installation Process

If the installation process was not executed correctly, such as mistakes made during partitioning or installation settings, it might have failed to clear all previous files. Verifying that you followed the recommended steps for a clean installation is essential. For instance, using a USB drive with the Windows Media Creation Tool may involve settings that unintentionally preserve existing files.

How to Remove Unwanted Files

To effectively reclaim that space, consider the following steps:

1. Check the Windows.old Folder: If this folder is present and you’re confident you won’t need to revert to W10, consider deleting it. This can be done through Disk Cleanup:

• Right-click on the C:\ drive in File Explorer.
• Select Properties and click on Disk Cleanup.
• Choose the option to clean up system files.

1. Manually Remove Old Files: Go through your Documents, Downloads, and any specific folders you may have kept during the installation to identify files that can be deleted.
2. Use Storage Sense: Windows 11 has a built-in storage management feature that can help automatically remove unneeded files and manage storage settings. Navigate to Settings > System > Storage to manage this feature.

By following these steps, you’ll be able to regain control over your C:\ drive, enhancing system performance and efficiency while ensuring that your experience with Windows 11 remains positive.