Preview Pane Not Working

[Reza3543]

Hi team,
The preview pane in Windows 11 stopped working. When attempting to preview a file, I receive the following message:

“The file you are attempting to preview could harm your computer. If you trust the file, open it to view its contents.”

Has anyone encountered this before? Any suggestions on how to restore preview function?
Thanks

[afipl]

Hi, I have the same problem. Some pdf can be previewed. But most not.
Waiting for a solution. This happended after last update.
Regards

[Jordan - PDF XChange]

Hello,

Thank you both for the report.

I have forwarded this for review by the development teams.

Once I have their feedback I will update this post.

[matteo2]

Same problem for me !

[Dimitar - PDF-XChange]

Hello,

As it appears, MS broke something again:


https://windowsforum.com/threads/window ... ws.384991/


Regards.

[wrhiltz]

Same error here.

[Dimitar - PDF-XChange]

We are waiting for MS to fix their bug.

So far, there is no news about when this will happen.

Regards.

[wrhiltz]

This fixed my problem.
Unblock the file and preview works fine.

image.png

[Dimitar - PDF-XChange]

Hi,

Unblock the file and preview works fine.

Yes, it does, but the catch is that you have to do this with all downloaded files

[wrhiltz]

oops. spoke too soon. Unblocking works for "some files" but not all.

And it is a pain to unblock files one at a time. I tried using an AI generated PS script to unblock whole directories, that didn't work either.

[Daniel - PDF-XChange]

Hello, wrhiltz

Yes... AI generated code of any sort has a tendency to run into that issue, and is why it is not recommended.. Especially when it is designed to perform security actions. Modern AI services you can find online are almost entirely "human language models", not coders/developers, they learn from wanton varieties of content that is freely available online - and often misuse what they have learned.

It is (unlikely, but entirely) possible that such scripts could mistakenly have very problematic calls in them, leading to larger security problems, or (MUCH more likely) try to make calls that are only available in a different language, such as using specific libraries that are not available to the function/language you actually need to use, because they do not properly understand context.

The Article Dimitar included a link to describes a few options that you have to circumvent this new windows "feature", including example scripts. I would recommend giving those some more careful review instead of using AI to do a task it was not designed to do.

Kind regards,

[Kobo]

Hi everyone, is there any news on this issue? There are workarounds, but how likely is it that Microsoft will make any improvements in the near future?

[Dimitar - PDF-XChange]

Hello Kobo,

Thank you for bringing this up.

Unfortunately, Microsoft has not yet taken any action to resolve the issue with File Explorer previews that appeared after the October 2025 Windows 11 update.

Some users have suggested temporary workarounds, such as:

- Rolling back the update if possible

- Using third-party preview tools

- Re-registering preview handlers manually via the registry, though this is not recommended unless you're comfortable with advanced system configuration


Regards.

[it@mastergrid.com]

Hello Dimitar,
Thansk fir your explanation, but could you share an exemple of registry file for preview handler with good key (if you can) for unlock enduser, please.
And if we need some varables, how can we find it.
Thanks.

[Dimitar - PDF-XChange]

Hello Kobo,

Possible workarounds until MS fixes the problem:


Re-register the Windows Shell Preview Handler
Advanced users can try re-registering the handler via Command Prompt:

Code: Select all

regsvr32 /u previewhandler.dll
regsvr32 previewhandler.dll

- (Replace previewhandler.dll with the actual DLL used by your PDF preview tool.)

https://www.pdf-xchange.com/knowledgeba ... extensions


- Roll back the update (if critical)

If previews are essential and none of the above work:

- Go to Settings > Windows Update > Update history > Uninstall updates.

- Find and remove the October 2025 update (KB number listed in the forum thread).

- Use a dedicated file manager

Apps like Directory Opus or XYplorer offer robust preview support independent of Windows updates.



..or you may just run this PS command on all of your PDF files:

Code: Select all

Unblock-File -Path "C:\Downloads\*.pdf"

Regards.

[Kobo]

Thanks for the additional information. Are there any security concerns regarding the PowerShell command? As far as I understand, it was intended by Microsoft as a security measure. Is it advisable to unblock all PDFs (for example, on a network drive) using this command?

Thank you for your time and effort.

[Sean - PDF-XChange]

Hi Kobo,

I'm afraid we can't make any guarantees about components that are developed by other companies - you would need to raise that with them, or in their forums.

Kind regards,