@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/vl91ji905drpywbxba2c6wccng2h4m... to http://www.plantuml.com/plantuml/png/~1vl91ji905drpywbxba2c6wccng2h4m... 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: vl91ji905drpywbxba2c6wccng2h4mpja9fkjccd9umw0lcjacgg2qwchc51iqdhkkayjasjjt3qqj8i uch-_7dlzxttip0h4707twl68xtj5weylail2ieyxntswqm4dagwsylvdgmwkt_zqfhz5zl6khpayai0 l8f4wakakeqo6f-qp-s1l44o9ot3xm0eor0a87yc2qh1-f4wriuq0hr88b4agk1ai5a25x7-fqybgdav lx6mmatnm2vb2t7i0vvuyxbwxoukiypmeic28rmpajhck0i9eyoehyhhkwwmcdd6exekyftkxvtog17i o2kxnyxnpvgcojn3n5pt8pnvmtjvk6fefrietvivs_ikuo-drltf5roeswg3stfdwinlrbw9lbhcpdle kiee5v-l7oiyfjakbc8hd6alx6tjw93z4qi-3nzcf7nmejrgcxuwyxvdi601cqiidmi7s-dx4vzc5-tt xs9mxqwtd7c3yvdzqhxfbqn8r8v7cr6fqonvgnm4dseb2_m3 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