Preview in macOS Big Sur is destroying PDFs

I have learned to be scared of my MacBook. Seemingly safe behavior can cause permanent damage. It does completely unexpected things, apparently by design.<p>I do not put my pictures in the ~&#x2F;Pictures directory for fear of what the newest app will do to “improve” them for me. I fully expect it to apply lossy compression to my files without asking. This is after Photos or whatever it was called at the time mangled the dates on a bunch of my vacation photos to 10 years before the actual trip.<p>Oh and have fun when your photos are automatically uploaded to iCloud to save space locally then silently deleted from iCloud to... save space? My sister lost her first year of baby pictures to that one.<p>Same with ~&#x2F;Music after iTunes wiped out a bunch of carefully curated metadata. Yes, I did want that album art.<p>I fat-fingered some key combination in Messages recently and got a prompt confirming I wanted to delete the entire conversation history. I consider myself lucky it bothered to ask.<p>I can add “view a PDF” to the list of things likely to leave me holding the bag.

Why anyone treats PDF as anything but a write-once format is beyond me. It&#x27;s so finicky that I&#x27;m not shocked bugs like this happen. The only programs I&#x27;d be reasonable sure wouldn&#x27;t screw it up are Acrobat itself, and pdflatex and friends.<p>I think we need a multi-image container format. It could be something that&#x27;s literally a bunch of jpgs&#x2F;pngs&#x2F;pick your poison in a tar container, and given a new extension. OSes would open it and present it as a gallery in order. There&#x27;s no value in a non-ocr&#x27;d PDF existing. For OCR&#x27;d text that gets more complicated, but it feels like we should be able to come up with a common denominator that doesn&#x27;t have the legacy of a binary format derived from postscript in the early 90s.

I work with a <i>ton</i> of PDF&#x27;s between my Mac and iPad, and it <i>mostly</i> works but there are still just <i>way</i> too many bugs.<p>It&#x27;s a lot of little things, like in Catalina where opening up the sidebar for annotations (comments) seemingly randomized their order. (Big Sur, fortunately, fixed it to be page-order again.)<p>Or how printing a PDF from a website (in Catalina, also seemingly fixed in Big Sur) would <i>look</i> right on the page... but if you copied and pasted the text from the PDF to somewhere else, something like 10% of the glyphs were scrambled (&quot;lik3 thZs&quot;), like some sort of character table corruption.<p>Or reading a PDF with Books on my iPad, maybe 10% of the time bookmarking a page... doesn&#x27;t bookmark it. Or removing a bookmark... doesn&#x27;t remove it. Or a handful of highlights you just made have inexplicably disappeared the next time you open the file.<p>Or whenever you open the PDF in Books it remembers which page you were on. Except <i>sometimes</i> it doesn&#x27;t, so you can&#x27;t really rely on that for saving your place.<p>Or in Books, if you select some text to copy but accidentally hit the adjacent &quot;select all&quot; in the pop-up menu, and you&#x27;re dealing with a 400-page PDF, it just locks up and you have to restart it.<p>Or in Preview if you want to convert a PDF to black-and-white, there&#x27;s an option for it but your PDF will balloon in filesize to 10x larger or something.<p>I mean, I could go on and on. It&#x27;s weird, because Preview is an <i>incredible</i> app, really. But it really is like they build it and then never bother to test if basic workflows reliably work.

This is a clickbait, sensationalist headline. “Saving a PDF with Preview in Big Sur can corrupt OCR text added by a third-party program” is more accurate.

I find posts like this completely pointless when they include no details at all. This is just &quot;there&#x27;s an incompatibility between third-party software and a version of macOS that the third-party software says they don&#x27;t support yet, so I&#x27;m going to publicly criticize Apple&quot;.<p>If you&#x27;re not going to do the work to figure out what the corruption is, at least include the two PDFs so other people can look at them and see what happened.

My guess is that the output PDF is still valid, but that an embedded (subset) font has had its `ToUnicode` map stripped, so that there&#x27;s no link between the character codes used in the text elements and the &quot;actual&quot; characters they represent (there are also other ways this corruption could happen, but dropping or mangling the `ToUnicode` map seems like a likely cause).

They are using software unsupported <i>by the vendor</i> and blaming Apple for the outcome.<p>“ABBYY says they don’t support Big Sur yet, that’s fine. But Apple didn’t tell me that I can’t upgrade to Big Sur when I use ABBYY. I’d be a lot less angry if there was a changelog or release notes from Apple where it says there is a known problem with OCR’ed PDFs in Preview. Their software is broken, they need to tell me. I don’t care if it only worked because they had workarounds for super shitty PDFs that ABBYY possibly produces, I just need my OS to keep working for me.”

I remember many years ago distributing PDFs as part of course material, that Adobe&#x27;s official reader would open just fine, but Mac&#x27;s built-in one wouldn&#x27;t (and simply fail with a useless &quot;an error occurred&quot; message.) Only a small subset of the class was using Macs <i>and</i> the built-in reader, so it took a while to discover. The problem eventually turned out to be some oddity in the way it treats whitespace[1], that Adobe and a few other readers were perfectly fine with, but not Preview.<p>[1] PDF is one of the strangest file formats I&#x27;ve worked with. It is a bizarre mix of binary and text, and some of the other design decisions are also perplexing.

I think the HN crowd has forgotten that the entire legal system uses PDFs, and in addition uses the redaction features of the likes of Adobe Acrobat, as well as others trying to squeeze in like FoxIT.<p>Redaction is huge in governments that have gone digital. Gone are the days where you print the paper, black it out, and then photocopy it.<p>I have worked with PDFs for a long time, and if you ever wanted compatibility, you had to use Adobe Pro, since there were so many bad PDFs with weird embedded stuff that only Adobe could read properly...because it was initially created in Adobe <i>sigh</i><p>All other products try to catch up, but they can&#x27;t clean up the mess that Adobe has left behind.

Preview seems like a good example of something that&#x27;s worth open sourcing. Not only will people end up doing work for you, you get eyes on the code and more direct issue tracking.<p>Consumers get a product and they still have to go on Mac to use it.

From what I can tell, there is no reason you can&#x27;t just run the PDF through ABBYY FineReader again and get the exact same OCR you got the first time, so I think &quot;irreversible&quot; is a bit over-the-top.<p>Is it as easy as CMD+Z? No. Is it data you can never get back? Also no.

This happened to me in Catalina as well. This summer I was preparing the paper proceedings for a conference, which were made with InDesign. I had to remove a couple of pages from the output, did so with Preview, and from then on, the text was garbled on copy-pasting. Had to switch to using Acrobat for that step.

Preview for PDF manipulation was a nice try at first, until I realized I suddenly have unexpected problems with produced docs, trouble with drag-and-drop, overwritten files etc..<p>Now I am using PDFGenius and never looking back.

Let&#x27;s be real. Every single macOS release, until it reaches x.y.4 or x.y.5 is just in beta and you are the tester.<p>I upgraded to Catalina when it hit 10.15.6, and I watched for the year since the release all the comments and posts about the horrible things it was doing to their computer, files, apps, etc.<p>Apple supports the latest 2 versions of macOS. Always be on the &quot;previous&quot; one is my advice. Since my family and friends started following it, they are much happier and more productive.<p>Let the masses beta test.

Apple has a lot of shit they need to fix in macOS and the accompanying apps.<p>That said, the author of this article is clearly an ass, and i have a hard time being sympathetic.<p>Assuming the pdf is actually in spec, which it&#x27;s probably not, this shouldn&#x27;t be happening. That said, if the 3rd party app vendor says the pdfs they generate are broken in big sur, that should tell you, they may be broken other places as well, and it&#x27;s probably not apple&#x27;s issue.

The text corruption doesn&#x27;t appear to be random. The same word gets converted to the same corruption. It&#x27;s more likely an encoding&#x2F;decoding bug.

Preview used to be solid, but it has been increasingly fragile in recent years. I found PDF Expert to be a great replacement. I have no affiliation.

&gt; You have to completely close the file and reopen it, only then will you realize that it has been destroyed.

At first glance, it’s a replacement cypher. Every ‘a’ becomes a filled square, every ‘b’ a ‘p’, every ‘c’ a ‘(‘, every ‘d’ a ‘)’, etc.<p>However, there are exceptions, for example the first ‘b’ on line 10. It becomes an ‘ä’ on line 21. I guess that’s because that is bold text, and thus a different font.

Once again, the Hacker News comments prove to be more useful and insightful than the article itself.

I had an issue recently where the form contents filled and saved with Preview.app would not show up in acrobat reader. I&#x27;ve encountered this in two cases so far, with two completely different documents.

I have encountered too man PDFs (mostly digital originals rather than OCRed scans) corrupted this way during the recent months. Now I see why...

I hate Preview&#x27;s PDF editing features, I wish there was a way to turn them off.<p>I&#x27;m the kind of person who tends to randomly click on things as I read them. In other PDF readers, this is quite harmless. In Preview, it starts editing the PDF. 99.9% of the time I have zero interest in editing or annotating the PDF I am reading. And then when I quit it asks me if I want to save a copy. I never wanted to change it to begin with!<p>(Maybe it is time I found another PDF reader...)

anyone else not able to see sufficient details the tiny screenshots? What was the difference?

Using Apple devices in general seems like a total crap shoot to me nowadays because of the impossibility of down-grading the OS. Every &quot;upgrade&quot; comes with a considerable risk that something that had been working will stop working, and if that happens, you are pretty much SOL.

Use &quot;Adobe Acrobat Reader DC&quot; for pdf work on macOS v11.1

Is this German?

Time machine?

Preview should not change the file on disk. I would expect it to open the original file as read-only.

PDFs are not intended to be modified. Preview and other readers use hacks to do the work. In general don&#x27;t modify the PDF and if you really want to do it buy Acrobat reader.

There was something in macos Catalina that broke mupdf on my macbook pro. The view would occupy the lower left corner of the window, and something was clipping the view to the lower quadrant.<p>I tried installing from source, changing the gl library etc. But it was the same.<p>Am done with Apple for now. M1 is a bit tempting, but I guess I will wait for the technology to mature, buy a Macbook Air, and run Linux on it.