Why do I see a “Project contains illegal migration devices” error in Quartus II software version 9.1 when Stratix IV GX/E production devices are specified as migration devices for a Stratix IV GX/E ES device in the same package?

You may see this error when you move your design from Quartus® II software version 9.0 SP2 or earlier to Quartus II software version 9.1 and later. Migration from a Stratix® IV GX/E ES device to a production device is disabled in Quartus II software version 9.1 and later due to different V_CC voltages between the ES device and non-ES device. The production device has a lower V_CC voltage compared to the ES device. Refer to the Stratix IV GX ES Errata Sheet and Stratix IV E ES Errata Sheet for more information.

To enable compilation, perform these steps:

1. Select the equivalent Stratix IV GX/E production device in Quartus II software version 9.1 and later.
2. Click ‘No’ when asked to remove location assignments.
3. Reassign the migration devices that you desire from the list of compatible migration devices for your current design’s target device.