Hi Sergei Shibanov,
PFB my answer of your queries.
Is it possible use only first two lines for reproduce issue?
Answer- Yes
Answer - HtmlString as read Html from File as string and pass it, which I have shared.
Htm…...IOException: Read-only file system : ‘/tmp/TempFonts’ at...Save(Stream outputStream, SaveFormat format) at CI.DataAggregation.Services...