I just upgraded to FM15 and am also getting error 800, unable to write to disk when using the save as PDF function. I am on Windows 10.
1) This happens with scripts that use a $variable (loop scripts that save to a designated location).
2) It happens with scripts that don't use a $variable path, that have dialog on to prompt user to name the PDF file and save.
3) And it also happens simply using the Save as PDF command from the File menu.
4) It happens with hosted files, as well as single-user local file.
5) I opened the same files using FM14 and everything works correctly - all scripts work fine.
I just restarted my system and installed the latest Windows 10 updates, but that didn't fix anything. Again, everythings work fine with FM14. I am about to do FM15 upgrades with several clients, but this is a major bug. Have others had this problem with the Save as PDF command on FM188.8.131.52?