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Andy sitycar0110
Participant
Oct 20, 2025 10:18 AM UTC
Question

No preview of PDF files in Explorer Office 365.

Hallo seit kurzem habe ich das Problem, dass ich keine PDF-Vorschau mehr erhalte. Es wird mir immer nur folgender Hinweis angezeigt. Das Problem ist mir erst seit kurzem aufgefallen, selbst bei selbsterstellten pdf erfolgt mal eine, und mal nicht. 
Es gibt erste Hinweise, dass das Problem bei Microsoft nach einem Update aufgetreten ist. 

4 replies

Tariq Dar
Legend
Oct 20, 2025 2:15 PM UTC

Hi @Andy sitycar0110 ,

 

Thanks for reaching out! The message you’re seeing is a standard Windows security prompt rather than an Acrobat error. It appears when a file is downloaded or shared from the internet or email — Windows marks it as “potentially unsafe” until you confirm it’s from a trusted source.

 

If you trust the sender or know the file is safe, you can remove the warning by:

  1. Right-clicking the PDF in File Explorer.
  2. Selecting Properties.
  3. Checking the box Unblock at the bottom, then clicking Apply and OK.

 

 

After that, reopen the file in Acrobat, and the message should no longer appear.

 

Hope this helps clarify the situation! Let us know if you continue to see the prompt even after unblocking the file.



Best regards,
Tariq | Adobe Community Team

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fmblux
fmblux
Participant
Jan 27, 2026 8:48 PM UTC

Firstly, I find the procedure suggested by Adobe to be rather cumbersome. With more than 100 PDFs to process per day, it is not feasible to select each PDF individually and change the properties accordingly. Secondly, this procedure is not possible in my case, as the “Unblock” function does not exist. Furthermore, I don't understand why PDFs stored in Synology and HiDrive are suddenly considered unsafe. Among other things, more than 3/4 of the PDF files were created by internal programs or documents were saved as PDF files as part of an internal scan. 

I will most likely cancel Adobe DC Pro if there is no practical solution here. Then I can also work with canceled programs.

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Souvik Sadhu
Souvik Sadhu
Legend
Jan 29, 2026 11:57 AM UTC

Hi ​@fmblux,

 

While we completely understand your frusttration, this started after an update from Microsoft.

There’s nothing we can do here to control how the OS behaves with files saved on the cloud or external storage.

 

The response shared by Tariq above is exactly the one Microsoft has suggested in its official post.

More info here: 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

 

Hope this gives more clarity.

 

Regards,

Souvik.

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