Reading Order Changes Cause Export Errors and Crashes

[ChronicDelusionist]

Summary
While exporting a large document that incorporates both Alt Text and heavily customized Reading Order, export with Tagged PDF on repeatedly either crashes Publisher entirely or produces an export error. Issue was able to be replicated by a third party using the free trial of Publisher 2.6.0.

Software Environment
Using Affinity Publisher 2.6.0, latest release version on Windows 11. Hardware acceleration is on, and I have tried turning it off; error persists. I have a WACOM Cintiq 16 installed, but to my knowledge the other party I asked to replicate the bug did not have any tablet firmware installed.

Details / Recipe
While creating a large file (almost 300 pages) and working it to be screen reader accessible, something I did while creating the Reading Order for the document has caused it to crash or throw up an export error (whether it's the crash or the popup is seemingly at random) when the PDF exports with Tagged PDF checked. I did a number of tests, as did a friend I sent it to, and we came to the conclusion that no matter what, the document would not export correctly and would encounter this error.

In addition, similar to bug AF-5086, the export preview will crash if left for longer than a few scant seconds. If we toggled off the Tagged PDF Boolean and raced through this screen, export would go through successfully.

We checked a number of factors (like preflight) and determined that the only throughline was the Tagged PDF toggle. I then dug up a backup of the project from before the Reading Order implementation but after the Alt Text implementation and it was able to export without issue with Tagged PDF checked. So the issue must be in the reading order somewhere, but I can't fathom why.

I've attached both the working document and the backup that exports clean below.

Pokeymanz.afpub Pokeymanz Pre RO Backup.afpub

Edited March 1 by ChronicDelusionist
clarifying that "at random" means that it crashes or shows an error, not that it randomly doesn't do it or not

[MikeTO]

I found the issue but it's a bit obscure which is why you couldn't find it in your document. Tables can't be excluded from the reading order in 2.6.0. Hopefully this will help you work around the issue until it's fixed.

1. Create a new document
2. Create a Table
3. Export to PDF with tagged selected = OK
4. For the Table article, Toggle Exclude From Reading Order
5. Export to PDF with tagged selected = crash

article export.afpub

Affinity Publisher 2 Beta-2025-03-01-133551.ips

[ChronicDelusionist]

MikeTO,

Thanks so much for the quick response. I've gone through my AFPub and changed it so (and then triple checked that) all tables are included in the reading order before testing export with Tagged PDF on again - no dice, unfortunately. Just to make sure it wasn't the artboards at the end of the document hiding a table, I pulled up the AFPub for them separately and ran an export test and they were able to be exported with Tagged PDF on just fine.

It appears that either I missed something, or the tables aren't the cause.

Pokeymanz.afpub

[MikeTO]

Tables were a cause, but I didn't have time to look further then. I'm taking another look now and there may be another issue. More to come...

[MikeTO]

I've narrowed an issue down to this page - again, there may be other pages with issues but this one is definitely a problem. There are two rounded rectangles added as articles. If either is excluded (the first was excluded in your document), it will crash on export.

I'm working to narrow it down further but if I remove the other objects from the page then it doesn't crash so it will take more time or Serif to figure out, but for now, don't exclude this rounded rectangle and if you still have issues then try to avoid using the exclude option. Alternatively, don't export as a Tagged PDF until this is fixed. Turning that option off in export will solve the problem. If it's crashing before you can get to the option, create a blank document, choose Export, and change the settings before trying to export your actual document.

2k.afpub

[ChronicDelusionist]

Alright, I'll mess around with the rounded rectangles and see if I can manage a workaround. I'll report back once I've tried with results. o7

Thank you for your hard work!

[ChronicDelusionist]

Update! I've been experimenting with the Rounded Rectangles. Flicking them on doesn't seem to impact screen reader usability, thankfully, so I was able to toggle them on in the Reading Order without issue. Unfortunately, this doesn't seem to fix the larger issue. While Page 10 (The one you sent me above as an example) is rescued by toggling the rectangle back on, Page 12 remains a sticking point with the exporter even with that fix.

It can't be the fact that it has connected text boxes, because the Table of Contents running text boxes over several pages have no issue. It can't be the Rounded Rectangle, because that's flicked on in the RO now. Other pages with images and captions export just fine, and most of the images are in PNG format to boot, so that's probably not it.

Curiously, when I copied over Page 12 to a new document via New & Add Pages from File, and took a look at the Reading Order, it ONLY lists the Rounded Rectangle despite obviously having all the other elements on the page.

Even more bizarre, we were able to find that both in the book and in the isolated page, the page would export fine if the image was removed. Even MORE MORE bizarre, in the pre Reading Order update backup, this page exports without any issue just like the rest of it. This is despite the fact that looking at the RO data, the actual order of the objects is no different on Page 12 between those versions EXCEPT that the ToC update was done between those versions (Meaning it used to be Page 9 in the backup).

There are other problem pages (like 16), but this is the first one I encountered after 10 so it's the case study, haha. what kind of dark wizardry is at play

Page 12.afpub

Edited March 2 by ChronicDelusionist
typo fix

[ChronicDelusionist]

I've continued to experiment to narrow this down. I performed the following tests on the 'dex image from Page 12 and its RO entry:

- I tried taking the equivalent page out of the backup document and inserting it in the main working document, and putting the RO entries from the old page back in the proper order in the document. Crash.

- I tried exporting the page while leaving the image's Alt Text on another line out of the export range, and leaving everything else on the page in order. No crash.

- I tried changing the alt text on the image itself. Crash.

- I tried copying and pasting the image's alt text to another image in the document and trying to export that page (11) instead with the replaced alt text. No crash.

Note: all of these tests were performed exporting the current page range of whatever page I was working on.

[MikeTO]

I don't know, but it's still related to exporting a Tagged PDF. For now, all I can suggest is leaving Tagged PDF off in the Export panel until it's fixed.

[Motljus]

46 minutes ago, MikeTO said:

I don't know, but it's still related to exporting a Tagged PDF. For now, all I can suggest is leaving Tagged PDF off in the Export panel until it's fixed.

Great thanks!

That simple checkbox fixed my export issues as well.

[Hangman]

Hi @ChronicDelusionist,

I think the main cause of the crash is possibly font related rather than specific to the Reading Order panel, though that's not conclusive...

I've identified 80 text layers over 70 pages and 4 image layers over 4 pages that will cause the file to crash when Tagged PDF is enabled. Three fonts, Barlow Condensed, OPTIRipple, and Optima, are common to the text layer crashes.

I don't believe the 11 tables in the document cause any of the crashes, more that the fonts used in the tables just happen to be Barlow Condensed and Optima...

In the attached file, I've highlighted the 84 affected layers by giving them a red tag and labelling them Problem Layer in the Layers panel, which means the same layers are easy to identify in the Reading Order Panel. Double clicking the objects in the Reading Order panel will also make it much easier to locate them in the Layers panel since sometimes they're not as easy to find because of their nested position within groups...

Although there are clear patterns which start to make it easy to identify the layers with issues, there is no immediate logic for the crashes. You can have the three fonts mentioned above crash one page but be quite happy on another, so I'm wondering whether the document is perhaps in some way corrupt...

I'll see if I can find any obvious correlation between the problematic layers and the Reading Order panel, and if I can I'll report back.

Without access to the Linked files, the attached version of the file both previews and exports with Tagged PDF enabled. It would be great if you could confirm whether the same is true once the graphics are relinked...

If the file exports without crashing, it's then a case of trying to work out whether or not this is font specific. One approach to that would be to replace the three seemingly problematic fonts in the original version with alternatives and to replace the problematic image files to see whether the file then exports. If it does, that would seem to point towards font issues. I'll test that tomorrow and let you know what I find out...

In the meantime, let us know how you get on with the attached file and whether or not you still experience the crash on export...

Updated File

Pokeymanz Tagged.afpub

[Hangman]

1 hour ago, Motljus said:

That simple checkbox fixed my export issues as well.

The problem with unchecking Tagged PDF when exporting the file is that your Alt Text will no longer be read by screen readers...

[ChronicDelusionist]

@Hangman - thank you so much for giving it an indepth look. Downloading your file, I found that the file indeed exported without issue when relinked to the images. Looking into the fonts, I found that doing a find & replace on the fonts you pointed out in the original documents (Barlow Condensed to Arial Narrow, OPTIRipple to Comic Sans MS, and Optima to Constantia, for the record), the crash still occurred on export.

The suggestion of corruption might be it, especially given that I've not had the same export issues with the backup files. As much as it would suck to have to redo heading structure and the reading order, it may be safer for the integrity of the files in the long run to just redo the work and periodically back up and check for any further corruption issues as I go. Luckily the Table of Contents seems to be unproblematic to re-insert.

And, yeah, I'm really hoping to get this exported with tags for accessibility reasons! So I was probably going to try and out-stubborn it even if that was the end of it, haha.

[Hangman]

@ChronicDelusionist,

Many thanks for confirming the file exports without issue once the images are relinked and thanks also for testing with font substitutions. That does then seem initially to point toward possible file corruption though I think now we know exactly which layers in the document are causing the issue it should be easier to test specific pages to see if there is anything obvious or common that could point towards a trigger…

As mentioned there are very distinct patterns to the problematic layers so that may prove to be a key but I’m equally keen to figure out whether the ROP plays any part in case this points towards a potential bug…

Let me know if you need a list of the affected pages as I have them all listed…

[ChronicDelusionist]

The file itself is helpful enough of a list for me! Like you said, It's all in red. I'm going to be redoing the Reading Order over the new few days and periodically stopping to do export tests, so I'll report back to this thread if any problems present themselves as I rework things back into their proper order. o7

[Hangman]

Perfect, do let us know how you get on, it will be interesting to know what you discover as you redo the reading order…

[Affinity Info Bot]

The issue "Export Tagged PDF with a table excluded from reading order will crash" (REF: AF-6085) has been fixed by the developers in the latest beta build (2.6.3.3273). The fix is planned for inclusion in the next customer release.
Customer beta builds are announced here and you can participate by following these instructions.
If you still experience this problem once you are using that build version (or later) please reply to this thread including @Affinity Info Bot to notify us.

[ChronicDelusionist]

A quick update before I put this one to rest - I ended up restarting my project from a checkpoint backup, and all was well with exports until the moment I started messing with the reading order again. Issues cropped up with the same images that caused issues in the first document, which suggests that if there was some corruption in the way the images are coupled to RO, that it happened long ago in the project history - possibly when the feature was first added to the already-done-document.

I was able to finish my work by switching back to the "bugged" version, isolating crash images (with the help from this thread!), extracting their alt text, and creating hidden captions to be visible only to screen readers and placing them in the correct order in the RO. No headings prevented export in my tests, just images with alt text. As before, no real pattern with what caused it.

I believe there is some sort of bug here, though whether it's something that only applies if you did alt text in the versions before RO was introduced, I don't know. But I figured I would log my experience here regardless.

It was NOT AF-6085, I can say that much.