How does a PDF become damaged?

[peterg76169565]

Recently I noticed that a few PDF files that had previously opened without any problems have become damaged. Acrobat now gives the message "There was an error opening this document. The file is damaged and could not be repaired." It definitely seems to be a problem with the file itself, not with Acrobat, since the file doesn't work when trying other PDF readers or other devices either. I'm certain that these PDFs once worked, and I haven't modified them in any way since then (in fact, I don't think they've ever been modified since they were created). Does anyone know how this could have happened?

[Dave__M]

Are you on a Mac?  The MacOS file preview app has made some PDFs 'broken' in the past.  I am not a Mac user, but have read here in these forums of this happening.  I'm sure other Mac users will chime in if this was/is an issue still.  Another thing to consider is if the PDFs have been manipulated and saved in software that is NOT Adobe Acrobat Pro.  Adobe can vouch for the behavior of their software, but not for applications that are not.  Not all PDF viewers/editors are the same.

I would also take a PDF that you can no longer  open, and see if they'll play nice on another computer.  There may be an issue with your installation (easy to fix)  of Acrobat.

My best,

Dave

[peterg76169565]

Thanks so much for your suggestions! But no, I'm on a PC -- sorry, I should have specified that. I've ruled out those other possibilities too.

[DeanUtian · Accepted solution]

There are many reasons why the PDF may have become corrupted. Were they on your hard drive or a USB memory stick? Something could have been corrupted on the storage device.

Here's a good article on this and possible solutions:
https://www.nucleustechnologies.com/blog/a-simple-way-to-repair-adobe-pdf-files/ 

[peterg76169565]

Thanks so much -- on reflection, I think this might be the exact issue. These PDFs were created (and initially stored) some months ago on the HDD of my previous PC -- very shortly before this drive was completely corrupted and I ended up getting a whole new PC. I transferred these files to the new PC via USB, but I'm now thinking they were already damaged before the transfer. (Fortunately, most of my transferred PDFs seem fine, and I was able to find an online service that *almost* completely repaired even these damaged ones). But yes, this didn't occur to me till after you posted this, so thanks again!

[DeanUtian]

Glad to help and very happy to hear you have not lost important information from the corrupt files.

This is another reason why backups are important and that means multiple copies in different locations.

[Bernd Alheit]

What can you see when you open the file in Notepad?