Internal Error: Sub-system: VPR20KMAIN, File: /quartus/fitter/vpr20k/vpr_common/place_constraints.c, Line: 815 - Internal Error: Sub-system: VPR20KMAIN, File: /quartus/fitter/vpr20k/vpr_common/place_constraints.c, Line: 815 Description Due to a problem in the Quartus® II software versions 11.0 and later, you may see this error when compiling a design with Physical Synthesis Effort level set to Extra . Resolution To work around this problem, either turn off Physical Synthesis or change the Physical Synthesis Effort level to Normal or Fast . The problem is scheduled to be fixed in a future release of the Quartus II software. Custom Fields values: ['novalue'] Troubleshooting novalue False ['novalue'] ['FPGA Dev Tools Quartus II Software'] novalue 11.0 ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']