This was reported before in T356510 and T333746, but closed as Invalid.

thumbnails do not appear on Wikisource, no matter purging is done:
https://en.wikisource.org/wiki/File:Literary_forgeries,_by_James_A._Farrer,_1907.pdf

Works for me after an ?action=purge and then attaching a nonsense parameter to the URL to force a cache bypass.

On https://en.wikisource.org/w/index.php?title=Page:Literary_forgeries,_by_James_A._Farrer,_1907.pdf/5&action=edit&redlink=1 error message shown:

Failed to initialize OpenSeadragon, no image found.

Cannot reproduce; page loads as expected here.

And this one ? https://en.wikisource.org/wiki/Index:Eddington_-_Stellar_Movements_and_the_Structure_of_the_Universe,_1914.pdf

https://en.wikisource.org/wiki/Index:Eddington_-_Stellar_Movements_and_the_Structure_of_the_Universe,_1914.pdf says
Source file must be fixed before proofreading

While https://en.wikisource.org/wiki/File:Eddington_-_Stellar_Movements_and_the_Structure_of_the_Universe,_1914.pdf renders for me.

But where exactly on which page am I supposed to see "Failed to initialize OpenSeadragon, no image found." ? A screenshot would be welcome.

In T434358#12211593, @Aklapper wrote:

https://en.wikisource.org/wiki/Index:Eddington_-_Stellar_Movements_and_the_Structure_of_the_Universe,_1914.pdf says
Source file must be fixed before proofreading

While https://en.wikisource.org/wiki/File:Eddington_-_Stellar_Movements_and_the_Structure_of_the_Universe,_1914.pdf renders for me.

But where exactly on which page am I supposed to see "Failed to initialize OpenSeadragon, no image found." ? A screenshot would be welcome.

This PDF now works. But the issue still exists for new PDF files. Please note that there is apparently no issue for this very big file: https://commons.wikimedia.org/wiki/File:Biblia_Latina,_Gutenberg_Bible,_LoC_copy,_vol._1.pdf which is quite weird.

Okay, so where to currently see a ""Failed to initialize OpenSeadragon, no image found."" error?

@Yann: Could you please answer the last comment? Thanks in advance!

Hi, Sorry, but this bug is completely random. It appears somewhere sometimes, and then disappears.

Hello, I've had a similar problem. The error appears on a "Page:" page, like here:

(You can ignore the text written next to Progress, that's an error message we manually set)

I tried using ?action=purge, that did nothing.

Then I opened a new private window (so not logged into my account) and it appeared normal on both pages with no error, however right after logging in, everything is the same as before (like in the screenshots).

I don't know if there is a way to "purge" some wikisource account cache or something to fix this?

I've also noticed this error tends to appear after a change was made to the source file, while the file still shows normally on commons, but I don't think that's always the case. The error has also appeared without changes to the source file. For me for example it randomly happend after proofreading some pages on here 3 days ago and hasn't gone away since, so I can't proofread anything there.