FlexNet Licensing error:-15, 10. Systems error: 10061 "WinSock: connection refused"

Description

You might see this error message after modifying an Intel® Quartus® Prime Software license file and not using a plain text editor.

Applications that are not plain text editors will automatically insert special characters which the service cannot read. 

Resolution

To avoid this error, use any plain text editor, like Vim*, gVim*, Notepad*, or Notepad++*.