You may receive this error when opening the MAX+PLUS II Programmer and selecting any FLEX® 10KE device using the Select Device command (Options menu). The Programmer and/or software may then close when you click OK.
You may also experience this problem when enabling support for the EPF10K50EFC484 device in version 9.12 of the MAX+PLUS II software. After selecting the EPF10K50EFC484 device and enabling the password, selecting OK may cause the above error to happen. The password is saved, and once the MAX+PLUS II software is closed and re-opened, it will function normally, and you can now generate Programmer Object Files (.pof) and SDRAM Object Files (.sof) for the EPF10K50EFC484 device.
No matter which FLEX 10KE device is selected, this process does not harm any existing files, affect compilation, or affect ByteBlasterMV and BitBlaster downloading.