4.1.2. Project Path Length Considerations
Design files with lengthy file paths might cause an internal error in the Windows* version of the Intel® Quartus® Prime Pro Edition software. Windows has a 260-character maximum path length limitation on the combined length of a file name and its file path. For more information, refer to Maximum Path Length Limitation.
To reduce the length of a file path to a design file, Intel® strongly recommends creating, storing, or moving your Intel® Quartus® Prime project to a shorter path. For example: