Mac OS X “PDFsam is damaged and can’t be opened”

Hi Mac users,
some of you reported the “PDFsam is damaged and can’t be opened” error when trying to install the PDF Split And Merge dmg package. After some investigation and users feedback I can finally write what is causing that. The issue is caused by a new feature of Mountain Lion and OS X Lion v10.7.5, called Gatekeeper which “help protect your Mac from malware and misbehaving apps downloaded from the Internet”. It does that by preventing you from launching apps that are not downloaded from the Mac App Store which is “The safest and most reliable place to download and install apps”. Now, assuming you still want to install PDF Split And Merge even if you didn’t download it from the “safest and most reliable place”, what can you do? As sorice pointed out you have to:

  • Open Gatekeeper settings located in “System Preferences > Security & Privacy”
  • Set “Allow applications downloaded from:” to “Anywhere” and confirm by pressing “Allow From Anywhere”
  • Launch Pdf Split And Merge
  • Once PDF Split And Merge is successfully launched, you can set back Gatekeeper option to whatever you want

Some more information can be found here



  1. Paul
    January 15th

    You can also control-click the package then select “open” – that way you don’t need to change your security settings.

  2. Lutércio
    February 26th

    My PC is Windows 7 64-bit, already downloaded the file needed to install the program PDF Split and Merge, but I’m not found the site necessary to disable security and allow the program downloaded from the internet to work anywhere.
    Can you tell me step by step of this operation?
    From now on, thank you.

  3. Jacqueline
    March 4th

    Thank you! Great it worked

  4. Kristina
    May 14th

    Thank you!!!! I love PDFsam and was sad I might be able to use it after switching to a Mac.

  5. Ulli
    April 19th

    Thank you, I love pdfsam!

  6. giz
    September 18th

    oh thanks

  7. Ana González
    February 11th

    I tried unlocking the app download on the Gatekeeper, but I still get this message from” The Unarchiver”: The contents of de file “PDFsam_Enhanced_Installer.exe” can’t be extracter by this program. Any help is welcome please!!

  8. Sofia
    July 14th

    does anyone know if it is possible, when using the split function within pdfsam, to have the split files have different names?
    Any tips much appreciated.

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