Due to a recent Windows update from Microsoft®, the Nios® II build flow using Windows Subsystem for Linux (WSL) is presenting issues during project compilation and download. Since EMIF generation needs Nios® II to build flow, you may see this error when generating any EMIF IP or Cyclone® V/Arria® V HPS IP with the Intel® Quartus® Prime Standard Edition Software version 19.1 or later versions for Windows. The failure has been identified in computers running Windows 10 Version 1903 and later.
Please first make sure WSL is installed in your Windows (NiosII Software Developer Handbook, 2.1 Installing Windows Subsystem for Linux (WSL) on Windows), then download patches for Intel® Quartus® Prime Pro/Standard Editions which solved a Windows 10 issue (see detailed in here).
Please make sure that only WSL1 is installed and not WSL2 which is not supported.