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/UDgDKzjkep0GVVTN-16KPhyWIjMzgb...tohttp://www.plantuml.com/plantuml/png/~1UDgDKzjkep0GVVTN-16KPhyWIjMzgb... 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: UDgDKzjkep0GVVTN-16KPhyWIjMzgbBQFYJAFa_C9B44Dh8DKPJjlw_17g0Eglg2cV7SpZaUnk1WdG7Xk2Z1MhwHBVu41_p6jd34PuS63YM-GBrwErWqBPhLRlt0oVXheAxHh7b57ijOgsN1BRezb0rcEzvsPnxSjRQfd-cGccta4SLLbFXsKMYuxhvZAz-NnqYJKyvlRT3RsNoGmKgtI7TV2hApK-GHb5PFmdcAifpiPmNaOGUjImJ5ps37SldK7RAdbqmgnq-UAszAhJBgL4XRWnDdgKw1heHnBfLq4fmsSHIXbPK5cbVjvF5w5pxYVMUfw6diZIsdL0tIiYL1gG8GjkochpPWQNwQ7Xs8yq1y734mjNNWyCSPr0cBZ0egl8II_Npq5gCGttMZ2YhcfqiKglfZKEX3_IJKwiO8V1XBV_lLeeU0tNVI-gcym3LHopSU0ruQr-q5hSlWngBNv9CreglLer-ZRJ-F__KiXtyxzeYN-tKFEMPvgngw3Yhjfoh5HIkR4n7Vg6Yzz-yDpH44VbYi6rj4-eYv7G-4351M_vRBEzo97OCI5XXBNrWVDgyl-uDUAIb6vOZ_pv9c6yofE06qy259tZXfg10aO7Sm5vEx_wzFts00