Description
Due to a problem in the Intel® Quartus® Prime Pro Edition Software v21.2, you might see this internal error when opening the register transfer level (RTL) viewer for designs targeting Intel Agilex® devices with imported partitions.
Resolution
To work around this problem, remove the "qdb" folder prior to compiling your design.
This problem is scheduled to be resolved in a future release of the Intel® Quartus® Prime Pro Edition Software.