When viewing some PDFs in Safari on a M1 Mac mini (running macOS 11.4), Safari shows a "Blocked Plug-In" page and the PDF is not shown.

This happens for example for this PDF, however other PDFs, such as this one work perfectly fine.

Following resolution steps have been attempted:

  • An existing Adobe Acrobat Reader installation was uninstalled completely from the System using App Cleaner
  • Files in /Library/Internet Plug-Ins/ or the corresponding user libraries were removed
  • The exstensions Page in the Safari preferences was checked, no active plugins were listed
  • All Website data has been deleted
  • The computer has been restarted after attempting each of the listed resolution steps.

What could be causing this blocked plugin message to appear only for some PDFs and what could be the solution to this issue?


2 Answers 2


I get exactly the same here. As we have nothing like the same Machine or OS, I doubt there's anything 'wrong' with your install.
This looks like some remote plugin was activated - some ancient Flash, Silverlight or Java etc, which have long been blocked in Mac & really shouldn't be unblocked.

It does work if you right click, download the link instead.

Poking at the page with debug tools I get

[Error] Refused to apply a stylesheet because its hash, its nonce, or 'unsafe-inline' does not appear in the style-src directive of the Content Security Policy. (KVSH-Newsletter_2021_06_11_Impf-Update11.pdf, line 0) [Error] Refused to load https://www.kvsh.de/fileadmin/user_upload/dokumente/Praxis/Praxisfuehrung/Newsletter/2021/KVSH-Newsletter_2021_06_11_Impf-Update11.pdf because it does not appear in the object-src directive of the Content Security Policy.

though I'm just stumbling in the dark in the developer tools, tbh.


I had this problem both on an M1 and an Intel Mac running macOS 11.4, and it turns out it was the Safari extension "Stop the Madness" that was causing this. https://apps.apple.com/us/app/stopthemadness/id1376402589?mt=12

Once I configured it to ignore the site where I was having issues, the problem went away.

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