@Hanooz: Thanks for reporting this. In the future please always use the bug report form and always fill in the sections in the template, instead of deleting them.

Also, please always do provide links as the bug report template requests.

https://commons.wikimedia.org/wiki/File:Divar.pdf

It looks like no images (of any pages) for that PDF are showing in the Page namespace, including when not editing: https://fa.wikisource.org/wiki/%D8%A8%D8%B1%DA%AF%D9%87:Divar.pdf/%DB%B7%DB%B7

This bug doesn't seem like it's related to the OpenSeadragon component in ProofreadPage, but perhaps somewhere like PageDisplayHandler::getImageTransform()? Or PdfHandler? If the PDF had its pages changed, I guess the old pagination is being cached somewhere?

• Pages not displayed: https://fa.wikisource.org/wiki/%D9%BE%D8%B1%D9%88%D9%86%D8%AF%D9%87:Divar.pdf
• Pages are displayed: https://fa.wikisource.org/wiki/%D9%BE%D8%B1%D9%88%D9%86%D8%AF%D9%87:KoliyatSaadiForoughi.pdf

This is probably something wrong with MediaWiki-extensions-PdfHandler or Thumbor. ProofreadPage and Openseadragon are thin wrapper around the API provided by them

Actually, this might be a duplicate of one of these:

• T315171: PDF file with good resolution appears as 0 x 0 pixel and page preview is not being shown
• T299521: PDF file has 0x0 image size in Commons after uploading a new version while the page number is correct
• T297942: Specific PDF on Commons has no image thumbnails, dimensions shown as 0x0 pixels

Which themselves might all be the same issue.

I think there is an argument for making the Openseadragon error less robotic 😄

The problem is that Openseadragon has no idea why the image did not generate and so has no way of knowing what went wrong :( We probably want to provide some kind of error serverside when this happens

In T333746#8757385, @Samwilson wrote:

Actually, this might be a duplicate of one of these:

• T315171: PDF file with good resolution appears as 0 x 0 pixel and page preview is not being shown
• T299521: PDF file has 0x0 image size in Commons after uploading a new version while the page number is correct
• T297942: Specific PDF on Commons has no image thumbnails, dimensions shown as 0x0 pixels

Which themselves might all be the same issue.

Yes, these seem the same. They should be merged.