Dear Maintainer, Files related to bugreport are attached in: GraphvizBugreport.zip I discovered that one edge was missing when generating PNG from dot file. See: broken.dot, broken.png There should be edge linking SampleSuperClass to SampleClass. It is declared in dot file on line: 104. If I just remove: style="tapered" Edge appears. See: workaround.dot, workaround.png This style is valid and is succesfully used in another edge, earlier in the file. It should not cause disappearance of the endge, so it must be bug.