Internal Error: Sub-system: U2B2_ROUTING, File: /quartus/db/u2b2_routing/u2b2_nd_routing.cpp, Line: 1681

Description

Due to a problem in the Intel® Quartus® Prime Pro Edition Software version 18.1 and earlier, you may see this internal error when running the Fitter Retimer stage or the Fast Forward Timing Closure Recommendations. This error occurs when the preservation level of a design partition is changed to final before running the Fitter Retimer stage or the Fast Forward Timing Closure Recommendations.

Beginning with version 18.1 of the Intel® Quartus® Prime Pro Edition Software, this may occur when one of the following Quartus Settings File assignments is set to ON.

• FLOW_ENABLE_HYPER_RETIMER_FAST_FORWARD
• FLOW_ENABLE_EARLY_PLACE
• ENABLE_FORMAL_VERIFICATION
• ENABLE_INTERMEDIATE_SNAPSHOTS

Resolution

To work around this problem, rerun the Fitter Retimer stage or the Fast Forward Timing Closure Recommendations and it will pass the second time.