Microsoft Confirms Default Lack of Functionality for File Explorer Preview Pane with Internet Files in Windows 11 25H2

Recently, Microsoft confirmed to Windows Latest that the File Explorer Preview pane in Windows 11 versions 25H2 and 24H2 will be disabled for files downloaded from the internet. This measure, motivated by security considerations, allows users to still preview locally created files, but restricts the functionality for online downloads.

For those unfamiliar, the File Explorer features two main panes: the Details pane and the Preview pane. The Details pane provides essential information about files, including the author and the date of creation, while the Preview pane allows users to glance at the content of a file without the need to open it. Activating the Preview pane is straightforward; simply click on ‘View’ and select ‘Preview.’

Users can click on a document to view its content on the right side of the File Explorer interface. Various file formats, like.docx and even Python scripts (.py), are compatible with this feature, enhancing the usability of File Explorer.

As long as the Preview option is selected, users can navigate through lengthy documents effortlessly:

File Explorer Preview Pane works for local files

However, attempting to preview files downloaded from the internet now results in a security alert:

The file you are attempting to preview could harm your computer. If you trust the file and the source you received it from, open it to view its contents.

This behavior affects all internet-downloaded files, as noted by Windows Latest.

Examining the Change: Why has the File Explorer Preview Pane been restricted?

Upon installing the relevant updates, I observed that many. PDF files in my downloads folder were not rendering previews. Instead, a warning message appeared, emphasizing the potential security threats associated with these files.

According to Microsoft, this is an intentional change aimed at enhancing user safety.

Understanding Microsoft’s Decision to Disable File Explorer Preview

Microsoft’s team has disabled previews for internet-downloaded files to mitigate security risks related to NTLM authentication protocols. In essence, should a user accidentally download a malicious file containing harmful links, the Preview pane could inadvertently expose their sign-in credentials. For instance, selecting a malicious file could prompt Explorer to fetch links from within it, potentially sending sensitive NTLM hash information to an attacker without the user ever opening the file.

Consequently, Microsoft implemented a policy change instructing File Explorer: “do not preview files from the internet.” This measure results in the warning users encounter when attempting to preview those files.

From Microsoft’s statement to Windows Latest: “With the Windows security updates rolled out on and after October 14, 2025, File Explorer will automatically disable the preview feature for any files downloaded from the internet. Users who are confident in the safety of the file and source can choose to remove the security block.”

To unblock a file if you trust it, simply right-click on the file, select Properties, and check the ‘Unblock’ box within the security section.

Unblock file in File Explorer Preview Pane

While this workaround is relatively easy, it undermines the primary advantage of quickly previewing files. The extra clicks required to unblock a file negate the convenience of using the Preview pane. Fortunately, users can expedite the process via a PowerShell script that unblocks all files of a certain type within a designated folder automatically.

For example, running the following command in PowerShell will unblock all PDF files in your downloads directory:

Unblock-File -Path "C:\Users\admin\downloads\*.pdf"

This script will apply to all current and future.pdf files in the specified path, given that users trust the downloads they make. Modifications to the script could be made for other file types or directories as needed.

This significant change is part of the broader updates released during Windows’ October 2025 Patch Tuesday, which also included issues affecting the Windows Recovery Environment and LocalHost.

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