ethtool -m on Intel X722 fails: Module EEPROM memory read not supported, please update the NVM image

On an Intel S2600WFT board the X722 10GbE SFP+ controller (rev 09, NVM 3.31 0x80000d31 1.1767.0) refused ethtool -m with Cannot get module EEPROM information: Invalid argument, and the kernel logged Module EEPROM memory read not supported. Please update the NVM image. The behaviour was identical with kernel 4.19.65 plus out-of-tree i40e 2.9.21, in-tree i40e 2.3.2-k and kernel 5.2.5 with i40e 2.8.20-k, while the same SFP+ module and driver worked on an X710. Follow-up on the e1000-devel list showed the required NVM is 6.01 (as on X710) versus 3.31 on the X722, but the NVM update tool 4.00 failed with configuration mismatches and flash verification errors, and the feature stayed unavailable after the attempted update.

• Hardware: Intel X722 (S2600WFT), Intel X710
• Transceivers: SFP+ module (unspecified)
• Form factor: SFP+

Symptoms / messages:

Cannot get module EEPROM information: Invalid argument
Module EEPROM memory read not supported. Please update the NVM image.