Description
Due to a problem in the Intel® Quartus® Prime Pro Edition software version 18.1 and earlier, you may see the above error message if your project has more than 250 encrypted IP source files and each fitter stage is executed separately, for example, quartus_fit --plan, quartus_fit --place, quartus_fit --route
Resolution
To avoid this internal error in the Intel® Quartus® Prime Pro Edition software version 18.1 and earlier, execute fit stage in a single step, for example: quartus_fit
This problem is fixed beginning with the Intel® Quartus® Prime Pro Edition software version 19.1.