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The PDF on the link below doesn’t open properly in my Sumatra. It works in Chrome and Edge, but becomes garbled in Sumatra.

Why, and is there anything I can do about it on my end, or is this a bug?



It doesn’t seem to be a bug.
I got a desktop message saying something about the document’s cache that needs to be downloaded on the pc (“client computer”).

Maybe the issue is related to compatibility. The document comes from an Apple user (Mac) and I have a Windows 10 pc.
The reason it opens in the browser is probably because it is opened by the Dropbox server.



Not “cache” but “patch” <^_^’)
The error message is “An error has occurred. Please make sure the current patch is installed on your client machine.”

I’ve checked for updates for Sumatra but it’s already the latest version.



The document is illegible i Sumatra. If I open it in Edge or Chrome i can read it.
It has nothing to do with where I get the document from. I have the same result when I get it directly from the source.

Now, it’s illegible not only in Sumatra, but also in OSX’ “Preview” app. But that doesn’t change the fact that I can read it in two browsers but not Sumatra.

So - and excuse my ignorance if you somehow already addressed this - what is it that makes it illegible in Sumatra and how can I get it to be legible there?


[LATER update]

This multi-lingual format appears now to be handled reasonably well by language layer default settings in version 3.2.

WOW never seen such a poor abuse of pdf layer feature, how would blind users chose which audio version to select, it may well show each regional version in a browser but that’s not “Portable” Document Format as intended

Unlikely MuPDF (the decode engine SumatraPDF uses) would choose which one of 16 languages to show thus it correctly shows ALL 17 layers one on top of each other

I would suggest the file should be issued as 16 separate files (one for each language)


OK, you confirm what I suspected: it’s a multi-language PDF (didn’t know that existed even). So the problem remains: it opens “properly”, or maybe not properly, but at least in a single language, in Chrome and Edge. So why not in Sumatra?


Sorry I did not elaborate further since I am not devoting time at present to disassembling this abomination, I will leave the forensics on this one to others,

It will most likely be an embedded java script which is run by chrome / edge that looks at the browser locale then changes layers on/off accordingly (it is thus a potential security vector as it can target selected users per region) It is not viral but closely “bordering” on it.

As a security measure SumatraPDF does not run internal java, it simply shows ALL standard visible content,

IMHO (in my humble opinion) I consider SumatraPDF is working correctly, and browsers are being manipulated (which most users may consider just as “correct” per their wishes).

If you want to check how java script can be controlled in other viewers (Acrobat, Foxit, PDF-XChange) see


Did you try to open this file in another PDF editor?