Command Failed Port Not Compatible Duplex Mode Online

If you issue duplex half on a 10GBase-T port, the command fails.

show etherchannel summary show lacp neighbor command failed port not compatible duplex mode

What are you configuring (Cisco switch, Linux server, etc.)? What speed are you trying to hit (100Mbps, 1Gbps)? Are you using a physical copper cable or a fiber SFP ? If you issue duplex half on a 10GBase-T