I don't seem to have this problem, and my copy of Windows 11 is completely up to date. Have you made any changes to File Explorer settings?
Is the Preview pane problem with pdf file display going to be fixed?
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Previously, when in explorer, simply clicking on the file name would instantly display the pdf file in the preview pane. In a recent update of Windows 11, this operation displays a warning about possible harm.
Windows for home | Windows 11 | Security and privacy
3 answers
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Bulldog 1,390 Reputation points2026-03-22T18:18:04.8733333+00:00 -
R R 0 Reputation points
2026-03-23T15:04:48.7233333+00:00 I have since learned that the problem was created from a Windows 11 update in October. The preview problem only shows up on pdf files downloaded after that date. I did NOT make any changes to File Explorer settings before I noticed the problem. I may have after the problem started while I was trying to solve the issue after it started. While there may be benefits to us all when a new update is "forced" on us, I usually only notice the downside of the update because there is almost always something that has worked forever suddenly stops working... Too bad we can't refuse updates
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R R 0 Reputation points
2026-03-23T15:20:28.86+00:00 Updates other than significant security updates....
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Bulldog 1,390 Reputation points
2026-03-23T18:03:43.4933333+00:00 I searched in File Explorer specifically for a PDF that was recently downloaded and I got the same result as you, so this issue is for real. Personally, it doesn't bother me because the Preview Pane is (for me) a convenience, but nothing more. I can still open these PDFs, and that's what matters to me.
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DaveM121 866.6K Reputation points Independent Advisor2026-03-22T16:24:16.6433333+00:00 This problem is caused by the October update, initially this was thought to be a bug in that update, however it is not, Microsoft have indicated on the link below that this is a deliberate security measure added in that October update and they have not indicated they intend to change that behaviour.
This forum is just a user to user forum, the best option would be to open the Feedback App in Windows and provide feedback to their support about this lack of functionality caused by that update.
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DaveM121 866.6K Reputation points Independent Advisor
2026-03-24T06:20:46.8266667+00:00 Glad to help!
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Q&A Assist2026-03-22T15:51:15.7966667+00:00 AI generated content. This question contains an answer created with AI from Q&A Assist. Learn moreThe behavior is by design and is not a bug that will be “fixed.” It was introduced as a security hardening change.
Starting with Windows security updates released on and after October 14, 2025, File Explorer automatically disables the Preview pane for files that are marked with Mark of the Web (MotW), which indicates they were downloaded from the internet or are being viewed from an Internet Zone file share. Instead of showing the PDF content, File Explorer displays a warning message:
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.
This change mitigates a vulnerability where NTLM hashes could be leaked when previewing files that contain HTML tags (for example,
<link>,<src>) referencing external paths. Attackers could exploit the preview feature to capture credentials.No additional steps are required to enable this behavior, and existing workflows are unchanged except when previewing files that carry MotW (typically downloaded files). The documentation does not describe any option to revert to the previous, fully automatic preview behavior for such internet-origin files.
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