File preview in Windows 11

What truly is maddening about this whole situation is...
1. Have not seen any word out of Microsoft that they are working on a "fix"
2. All of the 'patch fixes' I've seen rely on the PDF all being stored in one folder - give me a break.

I was about to yell at Adobe and now I want to scream at Windows!!!!!! I get they want to provide additiional security but give us more tech savvy users an option!  I hate having to open the file when I just need to look at something quickly.  I'm about to take a bat to my windows PC! sorry for the rage but lot of emotions right now

Microsoft should have blocked PDFs when it first came out... would have saved the world from a LOT viruses in PDFs... (and should have done the same for Flash for that matter).

According to the information from the KB5066791 update released on October 14, 2025, Microsoft has strengthened security measures for Windows 10, especially regarding the handling of files downloaded from the Internet.

🔐 Related content in KB5066791:
File Explorer automatically activates protection mode for files downloaded from the Internet or unknown sources.

When you try to preview or open these files, the system will display a warning as shown in the image you sent: “The file you are trying to preview may harm your computer…”

The goal is to prevent malicious code or dangerous software from being activated through the preview operation.

How to fix if you want to disable this feature:

You can unblock the file in the following way:

Right-click on the file → select Properties

In the General tab, if you see the line “This file came from another computer and might be blocked”, click Unblock.

Click OK to save the changes.

Unblock Multiple Files Using PowerShell
📌 1. Open PowerShell with administrative privileges
Press Windows + X → select Windows PowerShell (Admin)

📄 2. Run the following command to unblock all files in a folder:
powershell
Get-ChildItem "C:\Path\To\Folder" -Recurse | Unblock-File
🔍 Explanation:

Get-ChildItem: get a list of all files in the folder

"C:\Path\To\Folder": replace with the actual path to the folder containing the file you want to unblock

-Recurse: applies to subfolders

Unblock-File: command to unblock files

this was intentional by microsoft and it is horrible. 

Hi jctech2025,

Thank you for reaching out, and sorry about the trouble caused.

As the user gets an error message when opening files in preview, please check if the files are saved locally. Also, check if it happens with all PDFs. Try creating a new test PDF and then trying to open it in preview.

We would require more information to investigate this behaviour further. If you can share the screen recording, we can try replicating this issue. 

Please share the Acrobat and OS version in use.

Thanks,

Meenakshi