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/06tq404I5ENsC6cXKT6xxgxaBDG3o_...tohttp://www.plantuml.com/plantuml/png/~106tq404I5ENsC6cXKT6xxgxaBDG3o_... It will work this wayYou may contact the PlantUML team at plantuml@gmail.comBut you should also probably contact the plugin authors you are currently using and send them this image For the record, here is your data: 06tq404I5ENsC6cXKT6xxgxaBDG3o_tzkTRbkDJuRa4mYLIoIEFVZsapwhAr5NDHB0jrZfWK5MOp8y53KKy_J2adzUr-HCAJ8bVfEA7x6qMwXhNtcUJYCT4gMZV_c2gzJk9gimqo81bOfXLN-tkYpiaWi3aabF_wrItuxPLX5NINL6FKhAboWjmXbI8jiBfIRnXs0h40re09D-HpekC83iDO8GEXFHTCMoPlXmKCx05mLK_fTdsZCJY1geDzQhs6aar6qIIfU1V5QYHQ5wvIFj8v6xZE0zWeZksK6S5mgnjDR9L1ao9uZg7-gFLepB1EeGVeUILgETgbkEtuAelaPmmGV7kEDjEioz1d6D_0WvvYzGbScBwP8CnA9ZosEQ2vGlBk_7W00