Damaged PDF (error 14)

[Inélsòre]

Dear all,

I have spent the last two hours creating an interactive PDF for my music theory students.

I wrote all questions in Apple Pages (macOS 15.4.1), then exported the PDF and opened it in Acrobat.

Using the Form tool, I added several dropdown menus and carefully crafted them to cover all the questions they will face in the examination. Out of the form tool, I checked for each one of them to work, then saved the document and also opened it in Preview, where I also checked for it to be working. 

Suddenly, the file got damaged and I cannot open it anymore. 

The error, in Italian, is 

Errore durante l'apertura del documento. Si è verificato un problema durante la lettura di questo documento (14).

I absolutely have no time to remake this from scratch, especially if it will result in it becoming corrupted again. The file is attached below and I would appreciate if someone could help me diagnose what happened to it and possibly fix it in a way that I can use it again. 

Thank you very much!

[try67]

Preview is a terrible application when it comes to PDF files. It corrupts them just by opening them, although usually not to this extent. You should avoid using it, if at all possible.

I will see what I can do to recover your file, but I can't make any promises.

[try67]

This is the best I could do... It doesn't seem it would have had that many fields, though. Maybe 25 tops? Shouldn't take too long to re-create them.

[Inélsòre]

Thank you very much.

You managed to recover the 2nd and 3rd page but the first page has vanished, perhaps that's the one that caused troubles. 

The problem was not the amount of fields but that often each field had up to 30 items in the dropdown menu. 

I have never had this kind of troubles with Preview before, and it has never corrupted files for me before today, especially not on opening. But I will treasure your advice of course.

Any chance of the first page being recoverable?

Oh, and by the way, is the method you used to recover this shareable or is it some sort of philosopher's stone formula? 🙂 I would love to learn, nothing more. 

[try67]

The page dictionary was corrupt, which is probably why the first page was gone.

Regarding adding items to drop-downs: That can be very annoying to do manually. Which is why I developed a (paid-for) tool that allows you to import the data from a text file:

https://www.try67.com/tool/acrobat-import-items-from-a-text-file-to-a-combo-box-or-list-field

It will make your work much faster and easier, and I could adjust it so that it imports the values into multiple fields at once, if you wish.

I used I Love PDF's online tool to repair the file: https://www.ilovepdf.com/repair-pdf

[Inélsòre]

Forgive my ignorance but, what exactly is the "page dictionary"? 

If I recall correctly from my little training in basics of programming, a dictionary is a kind of data, such as "key:data", right? If this PDF's dictionary was corrupted, would it be possible to access the code which makes up the PDF and correct it? This is possible with SVG files or EPUB files, for example. Of course, it requires knowledge of what to do once that becomes available. 

Thank you also for the tool. 

I will use the two pages and rebuild the first one. Better than nothing I guess! 

[try67]

It's an element in the PDF file's structure that contains an array of references to PDPage objects. That array got corrupt so the applications could not find where to begin, hence the first page being "lost". The PDF format is WAY more complicated that EPUB or SVG, so fixing it manually is really not possible. You need to use a low-level library that can read, parse and write these streams to be able to identify and fix such issues.

The technical document that describes how to do this is more than a thousand pages long... It's a small miracle I Love PDF was able to do it at all. It's probably a common enough issue that they wrote a workaround for it.

I'd say take what you can get and make sure to always have a backup copy of your files, especially if you spend a lot of time on them.

[Inélsòre]

Thank you for explaining this. 

It's hard to backup a file that, after being created and opened a single time in a different application, becomes hopelessly corrupted. I will now create multiple copies of this file at least, or perhaps give it the "Stationery pad" option so that every time I open it it is a new copy, leaving the original intact.

One issue with the recovered file is that while some of the fields are there, they do not have the blue background that newly formed one have. Also, trying to attach the first page of the original PDF to this resulted in the file becoming corrupted again. Perhaps if you give a look at this file before I started to add fields to it you may find something useful.

Now I am working on a copy of this but with a different approach: instead of exporting from Pages to PDF, I'm exporting from Pages to Word, then opening the Word file into Acrobat. Why not doing this in Word, you say? Because I find Pages so much better than Word up to a certain level of complexity (which is mid-low, of course). 

[try67]

- I had no problem adding pages to this file and saving it. It opened fine after I re-opened it.

- If the fields aren't showing up then maybe the Fields Highlighting option is disabled.
To enable it go to Menu - Preferences - Forms and tick off "Show border hover color for fields".

- I strongly recommend you only convert your files to PDF using Adobe technology. The best way to do that is to drag your files into Acrobat (or use the Create - PDF From File command). It will convert them to a PDF file, if they are compatible with it.

If not, you can use the Export as PDF command, but that's not using Acrobat's software.

[try67]

PS. Have you tried using Time Machine on the original file? You might be able to restore a non-corrupt version of it...