User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.0.3 Safari/605.1.15
Steps to reproduce:
Open https://www.artecat.ch/jexler/moebius/moebius.png in Firefox 65.0.1 (observed on Mac OS X 10.12.6 "Sierra")
Firefox shows a black background with text "The image "https://www.artecat.ch/jexler/moebius/moebius.png" cannot be displayed because it contains errors."
The PNG opens fine in Chrome and Safari, as well as in Photoshop and Gimp etc.
The PNG contains an rather unusually large 5 MB zTXt chunk, which is likely the immediate cause of the error in Firefox (removing all "metadata" chunks from the PNG results in a PNG of 2.8 MB size that is displayed correctly in Firefox, see https://www.artecat.ch/jexler/moebius/moebius2.png ).
The images were produced by converting a PDF to PNG using ImageMagick, see https://imagemagick.org/discourse-server/viewtopic.php?f=3&t=35541
It is not 100% sure at the moment that the PNG is formally correct, but since all other applications tested could display (and/or edit) it, the Firefox behavior is likely not desireable: If an image displays correctly in most places it should ideally rather not fail in just one web browser, else creating web pages is made harder...
Is there a way to get more information behind the error in Firefox? It the error maybe a security measure that limits the size of certain chunks in a PNG to prevent attacks on the browser with images with huge such chunks?