This article describes why the "HTTP Error 500.19 - Internal Server Error" message appears in your web browser when you are trying to download an image from a Netboot server.
The deafult path is https://nebootserverIP/pmmimages
The error message is related to IIS Web Server. The server tells that it does not have permissions to get an access to the pmmimages folder.
1. You need to give local 'Users' group the next NTFS Security permissions on C:\pmmimages folder: Read&Execute; List folder contents; Read
2. Restart IIS Web Server.