Why can't I edit or upgrade my ALTDDIO megafunctions? - Why can't I edit or upgrade my ALTDDIO megafunctions? Description Due to a problem in the Quartus® II software version 13.0, you may be unable to edit or upgrade ALTDDIO_IN, ALTDDIO_OUT, or ALTDDIO_BIDIR megafunctions on 32-bit Linux systems. Specifically, you may be unable to open an existing megafunction for editing in the MegaWizard™ Plug-In Manager, or may experience failures when using the Upgrade IP Components feature. Resolution To work around this problem, use the Quartus II software on Windows or 64-bit Linux operating systems to edit or upgrade existing ALTDDIO_IN, ALTDDIO_OUT, or ALTDDIO_BIDIR megafunctions. Related Articles Error:Error in CNX file format. Can't create the custom megafunction variation file(s) Custom Fields values: ['novalue'] Troubleshooting novalue False ['novalue'] ['FPGA Dev Tools Quartus II Software'] novalue 13.0 ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']