Weird one-time bug with PDF with square root notation on Preview

I wasted 40 minutes trying to understand what do they mean in the calculus textbook with this notation.



Turns out, after quitting the Preivew app and opening the book again, that this was some loading issue of the pdf, and once loaded properly, these symbols (large bold 1 or 2 with a following "bar" or "roof") are square root symbols.



For context if useful: the book is hosted in my Books app on iCloud, I am at a train with fairly bad internet.


Why does it happen, will it be fixed?



[Edited by Moderator]

MacBook Pro 16″, macOS 15.6

Posted on Aug 27, 2025 07:47 AM

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2 replies

Aug 27, 2025 10:21 AM in response to IshayF

IshayF wrote:

I wasted 40 minutes trying to understand what do they mean in the calculus textbook with this notation.

Turns out, after quitting the Preivew app and opening the book again, that this was some loading issue of the pdf, and once loaded properly, these symbols (large bold 1 or 2 with a following "bar" or "roof") are square root symbols.


For context if useful: the book is hosted in my Books app on iCloud, I am at a train with fairly bad internet.

Why does it happen, will it be fixed?


[Edited by Moderator]



I might suspect a connection issue is the culprit(?) Get on a faster internet to compare your results and report back.


It would be impossible for me to try an duplicate the exact circumstances.


You would suspect the font data must be embedded within the PDF file at the time it is created. This makes the PDF self-contained and ensures that anyone can view it as intended, even offline(?) but I can not really speculate further.


To be proactive you can file a bug report / submit your Apple Feedback here: Product Feedback - Apple


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The current stable release of Sequoia including bug fixes, security updates is macOS 15.6.1

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PDFpen / Nitro

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pdfExpert

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Master PDF Editor

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PDFgear

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Foxit Reader / Editor

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Wondershare PDFelement

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Aug 27, 2025 10:19 AM in response to IshayF

IshayF wrote:


For context if useful: the book is hosted in my Books app on iCloud, I am at a train with fairly bad internet.

That is a very likely explanation.

Why does it happen, will it be fixed?

I thnk what you're seeing may be a glitch and not a bug. By "glitch" I mean something that went wrong for no discernible reason that doesn't happen again (or at least not for a considerable time). A bug, on the other hand, would be a flaw in the system that caused something, in this case, Preview, to work incorrectly. Apple really can't do much about the former. And they certainly can't fix the bad internet connection!


If you are regularly in spots with bad connections, make sure that the files you need are downloaded to your device beforehand.

Weird one-time bug with PDF with square root notation on Preview

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