Due to a problem in Intel® Quartus® Prime Pro Edition software version 19.1, you may see this Internal Error in a fitter stage for designs targeting Intel® Stratix® 10.
A patch is available to fix this problem for the Intel® Quartus® Prime Pro Edition software version 19.1. Download and install Patch 0.28 from the appropriate link below.
Download patch 0.28 for Windows (.exe)
Download patch 0.28 for Linux (.run)
Download the Readme for patch 0.28 (.txt)
This problem has been fixed beginning with version 19.3 of the Intel® Quartus® Prime Pro Edition software.