Internal Error: Sub-system: VPR20KMAIN, File: /quartus/fitter/vpr20k/vpr_common/cluster_greedy.c, Line: 3682

Description

Due to a problem in the Quartus® Prime Standard Edition Software version 18.1, you may see this internal error when compiling a design that instantiates one or more Clock Control Blocks(ALTCLKCTRL).

This problem occurs when targeting Cyclone® V devices. 

Resolution

To work around this error, remove the Clock Control Blocks(ALTCLKCTRL) from the design and fit the design automatically.

This problem is fixed starting with the Quartus® Prime Standard Edition Software version 19.1.