Known Participant

Question

File preview in Windows 11

Forum|Forum|3 months ago
October 22, 2025
6 replies
21890 views

Hi All,

I saw other threads on this issue where no one can preview PDF files in Window Explorer. I did a bit of troubleshooting and notice that is it only PDF files. Even after reinstalling I still get the same results for all the staff members:

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 it’s contents.

Where would this be coming from?

B

bgunn64

Participant

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.

L

leon_1300

Participant

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

K

Kim L

Participant

I agree whole heartedly. I thought it was Adobe and was ready to dump them for another pdf software, then discovered it’s not Adobe, it’s Windows. Because, I guess, previewing the contents of a file without clicking on it is a safety issue? I call BS. Clicking on a file then downloads the virus if it has one. Simply viewing it does not. This is intrusive and un-needed. I download a LOT of files every day (invoices, payments, etc.) and it’s too time consuming to individually unblock each file. I am switching to Directory OPUS. It’s not as “clean” as File Explorer, and takes some getting used to, but the time it saves me in previewing files was worth the learning curve. It does have an annual fee after a two month trial period, but it’s not an overly excessive amount, and again, the cost is made up in one day of not having to individually click on a hundred pdf files to preview them.

J

JO-CPA

Participant

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).

P

ph�_2423

Participant

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

A

AL214

Participant

Great information! Thank you! While I successfully did the Unblock for individual files, I need to unblock all files in my download folder, both current and future download files, but I don't understand exactly what I should put as the command. The command I used was Unblock-File -Path "C:\Users\seabo\Downloads\*.pdf, but that didn't work. Can you help me with the exact command for my PC to put in PowerShell please? Thanks so much for your time!

D

d_072

Participant

The command you should be using is: Get-childitem "C:\users\seabo\downloads" -recurse | Unblock-File

Make sure you opened Powershell as administrator.

C

Celine36808554op3a

Participant

this was intentional by microsoft and it is horrible.

J

Jordan$

Participant

Agreed. I'm convinced Microsoft hates creatives. Just like their terrible ACM, they take a sledgehammer approach to a complex issue that needs a scapel.

Meenakshi Negi

Community Manager

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

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