We are using the nuget package DotNet.Highcharts 4.0 in an (quite old) project. The chart is generating correctly, but when trying to download it as a pdf, the pdf is empty.
When clicking the download as pdf link, a http (not https) post request is made to 'export.highcharts.com' and the svg it sends in the form-data is a valid svg. Or at least it is valid when I save it to a svg-file and open it in Edge.
I can't find any information support has endend.
I discovered it has something to do with the http request made and a security feature from Firefox. It works fine in Edge (after ignoring a warningmessage about information being send over http). I can get it to work in Firefox also, but you need to set an advanced configuration property in
about:config -> dom.block_download_insecure = false. This is not something a regular user would know/can change.