Error: "one or more XREF chunks not found"

[kio]

Hello:

I've been getting this error for 2 or 3 times now, months apart, on multiple PDF files:
at a certain point (I can't figure out when or why), the PDF file decides not to open, and I lose all the comments I'd made when the PDF was working (highlighting, comments, etc.).

- I have Windows 10 Home, version 22H2, x64.
- I read in some of your forums that the problem might have something to do with HP, and my PC is an HP.
- I also read that there might be a possibility of sending the PDF file in .rar format.
If so, my corrupt PDF is 500 MB (it's several books combined). How would I send it to you?

Is there any way to repair it?
Thanks.

[Daniel - PDF-XChange]

Hello, kio

To begin, I will admit I have not seen this particular phrasing of an error message before, are you certain it says "typos not present" opposed to something similar? Perhaps it would help if you could send a screenshot of the error message you are seeing.

Following that, it would indeed be very helpful to see a copy of the document, since it is too large to send on the forums or by email, please upload the document to our file system here: https://files.pdf-xchange.com/s/D4L4D3xprZfxNct
(this link will only be valid for a few days)
Please post here to let me know as soon as the upload is complete, so I can take a look right away.

Finally, while there are some known issues with sending print jobs to HP printers, I cannot say I have heard of any HP computer specific issues which would influence our software to handle a document incorrectly. While I cannot fully rule it out (since HP is known to include a number of arguably useless background utilities on their devices [often called "bloatware"]), it is possible, though rather unlikely.

Kind regards,

[kio]

loil.png

l22.png

In addition to the 500MB one I just uploaded, I also found another corrupt PDF in the Windows recycle bin. (50MB),
which I can no longer open: and the problem is the same. And it happened to me with at least a third PDF file.
And I believe the problem isn't related to the PDF type (i.e., whether it's a PDF made of scanned JPG photos, or made from a Word file then converted to PDF), but rather it's a problem that happens whenever and however it wants.

I tried opening it with Firefox,
I tried merging a blank PDF page, along with the corrupted file, merging them into one,
I tried everything, but it just doesn't work.

[Daniel - PDF-XChange]

Hello, kio

Thank you for the samples - It seems that it was a fault either of Google translate, or the volunteer translator who handled this error message. The note the editor is trying to provide is "Xref chunk not found" - which is a much more familiar error message.

image.png

This message specifically, indicates that something has lead the document to be missing critical data formatting items.

This is most commonly done by software which does not respect the PDF specification (quite possibly, the "google books PDF converter" you are using, given that it is dated as a version from 2014). It is still today fairly common for utilities like this to have created a damaged file which is only noticed when a full features application like ours, recognizes the issue is present.
In all likelihood, there was always some content missing from this document, and something recently happened, which lead to a change in the document structure - that in turn removed some critical aspects and lead to the widespread damage you see now.

I should note that our software is quite actively aware of these issues, and does everything it can to fix them when we notice these errors (and signed of their precursors) are present, but nothing we do should be able to cause the problems directly, they would need to have already been present before we touched the file - and been damaged enough that we cannot fix them, which we try to do every time you save a document.

I am sorry to say that it is not possible to recover these files at this point. You will need to go back to the original copies (before they were converted to PDF) and try using a different tool for the conversion process. Something which properly understands the PDF Specification.

Kind regards,

[kio]

Okay, thanks, I think I understand.
I want to clarify (if I translated what you wrote into Italian correctly) that I didn't use "Google Books PDF Converter" (I didn't even know there was a specific PDF program made by Google). I don't have this program: I'm simply a random user who went to the "Google Books" website and downloaded some books from there.

I downloaded these two books from "Google Books," but I downloaded them as is, in PDF format, not in JPG format: that is, I didn't have the JPG images:

1.
And if I understand correctly, if I had had the individual JPG images of the book, I could then have used "PDF-XChange" to merge/assemble them into a single PDF file, which would have had no errors or corruption: (right?), because (this final PDF) would have been assembled by a more stable program (yours: "PDF-XChange") than the program Google uses to create PDFs ("Google Books PDF Converter"). Is that right?

The third book, which got corrupted at some point a few months ago (which I just sent you, and if I'm not abusing your time and availability, I suggest you look at it), consisted of eight individual books downloaded from the web (not from "Google Books"), which I then merged into a single PDF using your "PDF-XChange" program. So, if I understand correctly, this third book might also have the same error, eventually causing me to lose all my work? (As happened to me once months ago.)

2.
Is there a way/program/website/etc. where I can check, now in advance, whether other PDFs I've downloaded (from the web) to my PC also contain errors that could suddenly and unexpectedly appear, ruining all my work?

3.
If I download a 100-page PDF book from Google Books, which is truly damaged and corrupted, but I still don't know why I haven't seen the "...XREF chunks were not found" error message yet, and then I use your program "XChange" to convert this damaged PDF into 100 individual JPG image files, and then I merge/assemble those 100 images into PDF format, but this time using "XChange," will the final PDF obtained with XChange be free of the errors that the previous Google PDF had?

4.
Is there a definitive way, in short, that can permanently prevent these errors from appearing in all my PDFs?

Thanks again if you can answer these 4 questions of mine.

[Sean - PDF-XChange]

Hi Kio,

1. Yes, if you had JPG images of the pages of the book in question, and used those files to create a PDF with PDF-XChange Editor, then you would not encounter this issue.

Yes, it's possible that the "third book" you mentioned also has this issue.

2. I am not aware of any such program, and I would treat with caution any files from the problematic source.

3. Yes, that should be okay.

4. I'm afraid there is no way to foresee this issue. But creating the PDFs from JPGs, as detailed above, should be sufficient to avoid it.

Kind regards,

[kio]

Thank you.

I ask for your patience with these last questions, and I have definitively closed this topic.

1. I exported the 500MB Google PDF of 11,000 pages into individual jbig2 images.
2. I merged the jbig2 images with PDF-XChange, thus recreating a new PDF.

3. Now, if I optimize this recreated PDF and it reduces its size, e.g. from 500MB to 250MB, is there a risk that optimizing it will cause me to get the "Xref chunk not found" error, more often than if I didn't optimize it?

4. If I optimize it, since I have to insert thousands of comments (highlights, comments, arrows, etc.) into this PDF, is there a greater risk that the PDF will cause various errors or become corrupted more easily than if I didn't optimize it?

5. I will purchase the license for the November 20, 2025 version (10.7.6.404) and I am wondering: could the export to jbig2 (see: "number 1"), the image merging (see: "number 2") and the optimization (see: "number 3") be better and of higher quality than if I kept my current January 2025 version (10.5.0.393)?

6. Since I want to convert this 500MB file once and for all, without ever redoing it or touching it again, I am wondering: if I waited for your new version (the one after November 20), could the three steps described in "number 5" be even better and of higher quality, or would nothing change at all and therefore I just have to buy this one from November 20?

7. And if so (i.e., if the three steps of "number 5" could be even better and with higher quality), could you give me a rough idea of when the new version after November 20th might be released?

8. Finally, (since I have many other PDFs downloaded from Google, which I had already filled with comments [highlights, comments, arrows, etc.]), if rather than exporting to jbig2 (see numbers 1 and 2), I were to simply keep my old Google PDF (the one that gave me the "Xref chunk not found" error and which I had backed up) and rasterize it, (thus saving at least my old comments that I had already entered, without losing them), is there a risk that, sooner or later, the rasterized Google PDF will give me the "Xref chunk not found" error?

9. If instead I use the new PDF recreated with jbig2 (see "numbers 1 and 2"), we said that the error: "Xref chunk not found" should no longer appear: now, however, if the power suddenly goes off and the PC where I was working with the new recreated PDF suddenly turns off, without having been able to save my work, could this also corrupt this new PDF, and thus start creating the error: "Xref chunk not found" again, definitively ruining this new recreated PDF of mine too?

Thanks again for everything, and I bid you farewell, also thanking you for this PDF program which, in my opinion and for my use, is the best one on the web.

[Sean - PDF-XChange]

Hi kio,

1. and 2. - Okay, good.

3. and 4. Optimizing should not increase the risk of these issues.

5. and 6. I don't believe there is/will be any difference with regard to the features you mentioned.

7. The next release should be in the coming weeks.

8. It's not possible to know for sure either way, but the risk may remain with the document, yes.

9. It's not possible to say what might happen in that case, but I don't believe a power cut should make this error come back in the document.

Thanks and kind regards,

[kio]

Now I have an idea to save my previous comments, and that is:

1. I exported the 500MB Google PDF of 11,000 pages into individual jbig2 images.
2. I merged the jbig2 images with PDF-XChange, thus recreating a new PDF.

3. Now, can I export my comments (from the old Google PDF file, which I had backed up), into the new recreated PDF file?
Or could the comments in the old Google file also have been "spoiled" and "corrupted"?
And therefore cause the error: "Xref chunk not found", to appear also in the new recreated file?

[Sean - PDF-XChange]

Hi Kio,

You can certainly try exporting the comments from the old document and into the new one. Without knowing what caused the initial issue, there is no way for me to know if exporting/importing comments will be problematic. I'd suggest you make a copy of all documents before proceeding, and then simply try what you suggested and see if it goes okay.

Also n.b. the new build of our products - for which I belive you were waiting - has just been released.

Kind regards,