Description
Due to a problem in the Quartus® II software version 13.0 and later, you may see this error during synthesis if the design does not having any timing paths and Timing-Driven Synthesis is enabled.
Resolution
To workaround this internal error, switch off timing Timing-Driven Synthesis in the Assignments > Settings > Analysis & Synthesis menu.
This problem is scheduled to be fixed in a future release of the Quartus II software.