This is the instantcommons fallback, since the image is not present on enwiki it should be grabbed from commons. I was pretty certain that instantcommons works in Parsoid, I wonder what's going on. @Arlolra any ideas?

Further, it looks like this works on the command line:

$ php bin/parse.php --domain en.wikipedia.org --pageName Wikipedia:Wikipedia_for_Schools/Welcome/Mathematics --normalize=parsoid < /dev/null | fgrep versicolor
<div class="thumb"><span typeof="mw:Image"><a href="./File:Fisher_iris_versicolor_sepalwidth.png"><img resource="./File:Fisher_iris_versicolor_sepalwidth.png" src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1d/Fisher_iris_versicolor_sepalwidth.png/270px-Fisher_iris_versicolor_sepalwidth.png" data-file-width="957" data-file-height="638" data-file-type="bitmap" height="120" width="180" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1d/Fisher_iris_versicolor_sepalwidth.png/405px-Fisher_iris_versicolor_sepalwidth.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1d/Fisher_iris_versicolor_sepalwidth.png/540px-Fisher_iris_versicolor_sepalwidth.png 2x"/></a></span></div>

So this might be a misconfiguration (somehow) in how the rest_v1 endpoint is set up?

In T284570#7142615, @cscott wrote:

This is the instantcommons fallback, since the image is not present on enwiki it should be grabbed from commons. I was pretty certain that instantcommons works in Parsoid, I wonder what's going on. @Arlolra any ideas?

The other images on the page are also commons images so it's something specific to that image.

I did an ?action=purge and it seems to have fixed it. Maybe that image was recently moved to commons?

From https://commons.wikimedia.org/w/index.php?title=File:Fisher_iris_versicolor_sepalwidth.png&oldid=555722523

Imported with FileImporter from https://en.wikipedia.org/wiki/File:Fisher_iris_versicolor_sepalwidth.png

So, it existed on enwiki and Parsoid rendered the page and cached the result. And then got imported and deleted from enwiki.

Then, might be a duplicate of https://phabricator.wikimedia.org/T217540 ?

In theory we should have invalidated our cache when the image was updated. So that's probably still a Parsoid-core integration bug we need to track down and fix, probably. Or else it will magically Just Work when we move from RestBASE to ParserCache.