You may see either of the following two errors when migrating a design from a MAX® II device to a MAX V device:
Error (21191): Supply voltage value 2.5V set to the 'VCCINT' power rail is illegal for the selected device.
Error (21191): Supply voltage value 3.3V set to the 'VCCINT' power rail is illegal for the selected device.
In MAX II devices, there is a Quartus Settings File (.qsf) statement which indicates the VCCINT voltage used for the device. Valid values are 3.3V and 2.5V, and the value of this setting is used for power estimation.
MAX V devices require a 1.8V VCCINT voltage. When migrating a design from a MAX II to MAX V device, there may be invalid .qsf settings that remain in your project.
Remove either of the following statements from your .qsf:
set_global_assignment -name POWER_EXT_SUPPLY_VOLTAGE_TO_REGULATOR 3.3V
set_global_assignment -name POWER_EXT_SUPPLY_VOLTAGE_TO_REGULATOR 2.5V
If these settings do not exist in the .qsf for your project, then delete the db and incremental_db folders in your project directory and re-compile.