iOS 10.2 update breaks PDF viewer

Question

Level 1

9 points

iOS 10.2 update breaks PDF viewer

I have a customer that generates PDFs from our software that is emailed to him. The email contains an attached PDF which has tabular/grid data. This has been working just fine for him since iOS 7 through several upgrades. The customer upgraded to iOS 10.2 two days ago and on his Mac the PDF displays properly (as it always has), but on the iPhone the data in the table/grid is empty and just the outline of the grid and headers is displayed. I've check the format and is a simple PDF version 1.4 document. The customer has not installed or upgraded any software that generates these documents, so the only variable that changed is an iOS update.

iMac, OS X Mavericks (10.9.4)

Posted on Dec 15, 2016 1:04 PM

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Answer 1

llokodi

Level 1

4 points

Jan 4, 2017 12:22 AM in response to t_nelson

I did a little investigation and I found the technical cause, I try briefly explain: PDF uses deflate compress for stream (example page content) object, this method contains 4 bytes Adler32 checksum. The PDF readers (Acrobat, Foxit and prev iOS) does not check the Adler32 this means PDF producers do not calculate Adler32 (use '00000000' example) or checksum calculation is incorrect. I hope this help for PDF procuders...

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Answer 2

Jan 9, 2017 1:29 PM in response to t_nelson

The same issue here. We use applications that generate pdf views inside IE web browser. Normally these can be e-mailed to recipients from the browser with the adobe application. Now users have to save the file to their computer and then send the saved file so the recipient can view it. Nice that android users are unaffected by this issue.

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Answer 3

Jan 10, 2017 5:50 AM in response to llokodi

Thank you.

I can confirm that adding the correct Adler32 checksum fixed the problem of the missing text.

However I would still urge Apple to reconsider this change, since I could not find any other PDF viewer with the same problem. Nor does any PDF validator report missing or invalid checksum as error.

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Answer 4

Mar 13, 2017 1:39 PM in response to llokodi

We have the same issue. It started in 10.2 and still doesn't work in 10.2.1. I can open the PDF in Adobe and it works fine. I ran a Adler32 checksum on 2 PDF with issues, and a working PDF. All 3 files outputted a 8 character Adler32 checksum. How do I know if the checksum is valid or has a problem?

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Answer 5

Dec 21, 2016 10:24 PM in response to t_nelson

Having the same problem. Just updated to 10.2 and many of my PDF files are blank or do not display properly. I tried opening PDF files in my email, Ibooks, and PDF expert and they show blank.

I downloaded adobe acrobat and my PDF files display properly in it. Exporting these PDF files to Ibooks or PDF expert show up blank or not properly.

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Answer 6

dephex

Level 1

4 points

Jan 3, 2017 1:18 PM in response to t_nelson

I am having the same issue. By any chance are you generating the PDFs using ActiveReports?

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Answer 7

Rhand5

Level 1

11 points

Jan 7, 2017 1:22 PM in response to t_nelson

Has anyone found a fix yet? I have a couple of different PDF viewer and apps on my iPhone and I still can't see anything after the latest update.

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Answer 8

Jan 12, 2017 5:13 PM in response to llokodi

Thanks for the investigation and detail above.

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Answer 9

mteguh

Level 1

4 points

Jan 20, 2017 11:12 AM in response to Chulio Martinez

Where should the Adler32 checksum get added? In the app or in the stream?

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Answer 10

llokodi

Level 1

4 points

Jan 20, 2017 11:31 AM in response to mteguh

Adler32 is part of the deflated stream object.

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Answer 11

llokodi

Level 1

4 points

Feb 6, 2017 11:02 PM in response to llokodi

I upgraded my iphone to 10.2.1 and I think Apple fixed the problem, I can view "bad" pdf files, but I did not find related info or doc in Apple notes.

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