Here's Why File Explorer Doesn't Show You Preview Pane for Downloaded Files

If you’ve been wondering why File Explorer suddenly stopped showing previews for files downloaded from the internet, we may finally have an answer, all thanks to Microsoft.

As part of the October 2025 Patch Tuesday rollout, Microsoft quietly changed how File Explorer handles files tagged with the Mark of the Web (MOTW). For the unitiated, MOTW is a security flag that marks content originating from the internet.

With this update, File Explorer now automatically disables the preview pane for such files by default. According to Microsoft, the update has been applied to block a critical vulnerability that could leak NTLM hashes (sensitive credentials used for authentication).

This could happen when you preview potentially unsafe files containing HTML tags that reference external resources. In simple words, just by previewing a malicious file, you could expose your system credentials.

With this update in place, you will see a warning message stating:

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.

Remember, this restriction applies only to internet-downloaded files, while local or network files remain unaffected. For those who trust the source, it’s still possible to manually unblock a file. You can simply right-click it, select Properties, and check Unblock to restore normal access.

via: Neowin