While fixing the test [1], I found that the following data uri cannot be parsed because the fill attribute contains the hash '#' character. It can be reproduced by copy and paste the following to the url bar. data:image/svg+xml;utf8,<svg width="100px" height="100px" version="1.1" xmlns="http://www.w3.org/2000/svg"><path d=" M 0.00 0.00 L 50.00 0.00 C 50.00 33.33 50.00 66.67 50.00 100.00 L 0.00 100.00 L 0.00 0.00 Z" fill="#006400" /></svg> If I substitute '#' by '%23', it works fine. This seems like a bug because the ' ' space character is escaped. Google Chrome has no issue parsing this, btw. [1] https://dxr.mozilla.org/mozilla-central/source/testing/web-platform/tests/css/css-shapes/shape-outside/shape-image/shape-image-002.html

# is reserved as the start of a fragment identifier (https://en.wikipedia.org/wiki/Fragment_identifier). Chrome is buggy but the Chrome developers already know.