PDF document is damaged and cannot be repaired (Acrobat Pro/Reader, MacOS)

[Jeffrey Dean]

I have been getting this error message on a number of PDFs. The first one this happened with will open OK in Acrobat Reader but not in Acrobat Pro; more recent ones won't open with either, but will open OK in Apple Preview or PDF Expert. I am running MacOS Ventura 13.2 and the latest versions of Acrobat Pro and Reader. I have found this explanation in Adobe Support: https://helpx.adobe.com/acrobat/kb/pdf-error-1015-11001-update.html#, which looks like it would solve my problem if I knew how to implement it. I am reasonably comfortable with Terminal, but I have no idea how to achieve the recommended actions. How do I "use a similar method on Mac OS by modifying the same plist preference" or "create a DWORD"?

[Karl Heinz Kremer]

Here is information about the the same concepts on the Mac: https://www.adobe.com/devnet-docs/acrobatetk/tools/AdminGuide_Mac/macintosh_deployment.html?highligh... 

As the original article says, this will be done in a Plist file (specifically ~/Library/Preferences/com.adobe.Acrobat.Pro.plist). You need a Plist editor, there is one included in Xcode. 

Before we do that however, let's figure out if this really is your problem. Open the PDF file in question in NotePad and look at the first line. Does the file start with %PDF- followed by a version number? If so, this is is not your problem. If it does not start with %PDF, can you find the string "%PDF-" (without the quotes) in your file? If so, how far from the beginning of the file is it? 

[Jeffrey Dean]

Many thanks! I opened it in BBEdit; line 1 is "%PDF-1.5". So if that wasn't the problem, where else should I be looking?

The file in question (which, I repeat, does open OK in Preview and PDF Expert) is one of several that I produced from IIIF manifests of digitized medieval manuscripts using the online tool PDiiif (https://pdiiif.jbaiter.de/). Others from the same general source (https://www.e-codices.unifr.ch/en) open in Acrobat without problems.

I'm in the process of installing Xcode.

[Test Screen Name]

Can you share one specific PDF that shows this problem for you?

[Jeffrey Dean]

They're all very big, mostly in the 4GB range; the smallest I have to hand is 1.79GB.

[Karl Heinz Kremer]

In this case, you may actually have a corrupt PDF. Just because other PDF viewers are opening these document does not necessarily mean that they are not corrupt. Acrobat is a very powerful application and because of that, it is much pickier about the quality of PDF files than very simple viewers - or older versions of Acrobat/Reader. As TSN suggested, if you do have a file that you can share, we can poke around in it. 

[Jeffrey Dean]

I do have the biggest of these problem files open in BBEdit. Since I can't upload it, can you suggest where I might look? Would a Dropbox link to one of the smaller files be helpful?

[Jeffrey Dean]

Right — it took a while for Dropbox to sync. Here's the smallest of the files:

https://www.dropbox.com/s/r9knxnv0fo1d76b/Estavayer-le-Lac%2C%20Paroisse%20catholique%20Saint-Lauren...

Can you see where the corruption may lie?

[Karl Heinz Kremer · Accepted solution]

This is a massive file, and unfortunately without spending a huge amount of time, it's impossible to figure out exactly what's wrong. Unfortunately, when you open the file in Preview and export or save it, it still shows the same problem in Acrobat. I found one way to fix the file, but it does require a few steps: The open source Apache PDFBox library comes with a few applications, one of them is a split function. I used that to split the document into one page individual PDF files (it may also work with larger chunks, I have not tried that), and then combined them in Acrobat into a new PDF file. After I saved that file, I was able to open it in Acrobat without the problem. The filesize is similar, that suggests that the content has not changed. You can find PDFBox here: 

https://pdfbox.apache.org/

Here is information about how to use the split function: https://pdfbox.apache.org/2.0/commandline.html#pdfsplit

I would get in touch with the people behind the PDF creator that you've used and see if they are aware of problems with large files and recent versions of Adobe Acrobat. 

[Jeffrey Dean]

Thank you very much! I'll try what you've suggested with PDFBox. I will get in touch with the developer of the PDF creator as you suggest. I don't think the problem is to do with file size as such, since in another case 7 of 8 similar files work fine in Acrobat, and all 8 are over twice the size of the one I shared. But there's a "Report a problem" button on the web page, and I'll use that.

[Jeffrey Dean]

Success! It took a little trial and error, but I've now managed to reconstitute several files, splitting into 128-page chunks and combining with the PDFMerger function in PDFBox. I'll get in touch with the developer next.

[Karl Heinz Kremer]

Glad that this worked out. PDF is a pretty complex format, and there are many things that can go wrong. It may not be the filesize in general, but for example the size of the individual images, or something else that causes a problem. It is also possible that there is a bug in Acrobat, but unless we know exactly where it happens, it's impossible to determine if it's the PDF or the application. 

[Jeffrey Dean]

I understand. I'm very grateful that you took the time and trouble to help me.

[Ngoc le]

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[le_3969]

My pdf file start with %PDF-1.7.

I try what you've suggested with PDFBox. But when I split file, I got error "Error splitting document [IOException]: Missing root object specification in trailer.Error splitting document [IOException]: Missing root object specification in trailer."

[Karl Heinz Kremer]

The error you are seeing would point to a serious problem with the PDF file. It is possible that your PDF is too damaged for any simple attempts to repair it. You could try to find a PDF tool that can open the file and then either save from that tool and hope for the best, or convert to another format, or print to a vitual printer that can convert to e.g. images. Once you have for example image files, you can then import those again into Acrobat and convert to a PDF again. But again, you might be out of luck. 

[le_3969]

Thank you very much.

I checked my pdf file, it start with %PDF but not end with %%EOF.

I try to use tools repair online,  some tool work but font not displaying properly.

[Karl Heinz Kremer]

This means that part of your file is missing (or severely corrupt), which means the missing/corrupt data cannot be recovered. Your problems with the font may be a symptom of that.