@startuml legend The plugin you are using seems to generated a bad URL. This URL does not look like DEFLATE data. It looks like your plugin is using HUFFMAN encoding. This means you have now to add an header ~1 to your data. For example, you have to change: http://www.plantuml.com/plantuml/png/SoWkIImgAStDuG8oX221YIajB4a_A5... to http://www.plantuml.com/plantuml/png/~1SoWkIImgAStDuG8oX221YIajB4a_A5... It will work this way You may contact the PlantUML team at plantuml@gmail.com But you should also probably contact the plugin authors you are currently using and send them this image For the record, here is your data: SoWkIImgAStDuG8oX221YIajB4a_A5L8B-HGLYDEKlDI24ci3gS1x5_LpF1Io4ZDoY_Lggf8B4aTQmE5 qF9JKe5IWSy5B4dCJqafAawX2a_8Ab-gLz2kGcmwXq_54p2vB3L9paa9t17GbANbLqAP3A1L2bK7s_gY kMv_S-O5B6eQG-C1LgYk4GMGk9pmwH89Q5wK4L2y8I2z9nGY9GIP-zXFve3r4W4m00 endlegend @enduml Submit amiga aws-orange black-knight bluegray blueprint cerulean-outline cerulean crt-amber crt-green cyborg-outline cyborg hacker lightgray mars materia-outline materia metal mimeograph minty plain reddress-darkblue reddress-darkgreen reddress-darkorange reddress-darkred reddress-lightblue reddress-lightgreen reddress-lightorange reddress-lightred sandstone silver sketchy-outline sketchy spacelab spacelab-white superhero-outline superhero toy united vibrant       🎉 Discover the future PlantUML Web Editor! 🚀  PNG  SVG  ASCII Art