Thank you for the journals @filip.kabelis!
From reviewing the provided journals, it looks like you are using the third party add-in ProSheets to export to DWG: Jrn.RibbonEvent "Execute external command:CustomCtrl_%CustomCtrl_%DiRoots%ProSheets%ProSheets:ProSheets.PSCommand"
From part of the exception that is occurring (const class AString), I’ve found a similar article which relates to saving to a path that is too long (more than 260 characters)
First, I would suggest trying to save the DWG to a location on your local C:\ with a relatively short path (e.g. C:\Temp\filename.dwg). If this works, check the original path length, and see about using a shorter path.
If this doesn’t help, try exporting to DWG using the built in DWG export File-> Export -> Cad Formats -> DWG to see if you get a different result.
Lance Coffey
Technical Support Specialist