Overview
Microsoft recently released a Windows security update that changes how File Explorer handles files downloaded from the internet or email. After this update, some files will no longer show a preview in the preview pane. This is expected behavior and not an issue with your computer.
Downloaded files are marked by Windows as “from another computer,” which means they are treated as untrusted. The new update blocks previews for these files to help protect you from opening unsafe or harmful content. Once a file is marked as trusted, the preview will work again.
How to Fix Preview for a File
If you trust the file and want the preview pane to work again:
- Right click the file.
- Select Properties.
- In the General tab, look for Unblock at the bottom.
- Check Unblock.
- Click Apply and OK.
Note: You cannot unblock multiple files at once using the Properties window. Windows only allows unblocking one file at a time through this method.
If You Have Many Files Affected
If this is happening across a large number of files or an entire folder, our support team can help. We can run a script that safely unblocks many files at once while keeping Microsoft’s security update in place.
If you would like this done, please open a support ticket.
Important
We do not disable or undo Microsoft’s security update. Unblocking files individually or requesting a bulk unblock are the only supported options.
Supporting Information
For more details, you can review Microsoft's public documentation:
https://support.microsoft.com/en-us/topic/file-explorer-automatically-disables-the-preview-feature-for-files-downloaded-from-the-internet-56d55920-6187-4aae-a4f6-102454ef61fb