opening old pdfs after OS upgrades

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opening old pdfs after OS upgrades

After a few OS upgrades (I'm on Catalina now) I have become aware that I have a lot of older pdf files that will no longer open, either in Preview or Adobe Acrobat Reader (they are greyed out under Open). I'm not sure which upgrade created the problem, or how old pdf files have to be before I cannot open them, but I have no problem opening ones created in the last few years. All I know is that until the last few upgrades I could still happily open pdf files going right back to the 1990s.

Are the files permanently irrecoverable now?

iMac 21.5″, macOS 10.15

Posted on Jul 18, 2021 4:57 AM

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Answer 1

Jul 18, 2021 6:36 AM in response to fordwich

Does the icon look the same as the newer PDFs?

Try adding a .pdf extension, if they don't already have one.

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Answer 2

Jul 18, 2021 7:36 AM in response to fordwich

Are you sure they are pdf's?

Change the extension to .doc and see if word (if you have it) or Pages can open it.

Otherwise, get a binary editor (look in the App Store for "hex editor") and look at the header to see what you see:

https://resources.infosecinstitute.com/topic/pdf-file-format-basic-structure/

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Answer 3

fordwich Author

Level 1

6 points

Jul 18, 2021 7:15 AM in response to Keith Barkley

Thanks for the response.

No, the icon is not the same. Once I tried adding the .pdf extension to a file, as you suggested, the icon changed to the newer one, but the file still wouldn't open. The message given was: "The file “.pdf” could not be opened. It may be damaged or use a file format that Preview doesn’t recognise." (Acrobat wouldn't open it either)

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Answer 4

fordwich Author

Level 1

6 points

Jul 18, 2021 8:06 AM in response to Keith Barkley

I think you're right that the majority of the files in question - although they have 'Adobe Acrobat Reader DC Document' descriptors in 'Kind' - were Word documents originally. However, if I try adding the .doc extension they still won't open (in Word).

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opening old pdfs after OS upgrades

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