Due to a problem in the Quartus® II software version 12.0 and earlier, you may see this error when compiling a design with imported Quartus II Exported Partion (.qxp) files. This error occurs when the software reads the Memory Initialization Files (.mif) for the RAMs or ROMs referenced in the .qxp. These .mif files are supposed to be in the db directory after importing the partition, but they are missing.
To work around this problem, copy the missing .mif files into the db directory.
This problem is fixed beginning with the Quartus II software version 12.1.