Hi There Hope some one can help and encountered this before. 
I followed https://os.mbed.com/teams/ST/wiki/How-to-enable-flash-dual-bank to enable dual backs. 
I unchecked in nDBANK over STLINK. 
And added my mbed_app.json is :
{
    "config": {
        "network-interface":{
            "help": "options are ETHERNET, WIFI_ESP8266, WIFI_IDW0XX1, WIFI_ODIN, WIFI_RTW, WIFI_WIZFI310, WIFI_ISM43362, MESH_LOWPAN_ND, MESH_THREAD, CELLULAR_ONBOARD",
            "value": "ETHERNET"
        }
    },
    "target_overrides": {
        "*": {
            "target.features_add": ["COMMON_PAL"]
        },
        "NUCLEO_F767ZI":{
            "flash_dual_bank": "1"
        }
    }
}
When Compiling I'm getting :
"Error: Attempt to override undefined parameter 'app.flash_dual_bank' in 'application[NUCLEO_F767ZI]'"
                    
                 
                
             
        
Hi There Hope some one can help and encountered this before. I followed https://os.mbed.com/teams/ST/wiki/How-to-enable-flash-dual-bank to enable dual backs.
I unchecked in nDBANK over STLINK.
And added my mbed_app.json is :
{ "config": { "network-interface":{ "help": "options are ETHERNET, WIFI_ESP8266, WIFI_IDW0XX1, WIFI_ODIN, WIFI_RTW, WIFI_WIZFI310, WIFI_ISM43362, MESH_LOWPAN_ND, MESH_THREAD, CELLULAR_ONBOARD", "value": "ETHERNET" } }, "target_overrides": { "*": { "target.features_add": ["COMMON_PAL"] }, "NUCLEO_F767ZI":{ "flash_dual_bank": "1" } } }
When Compiling I'm getting : "Error: Attempt to override undefined parameter 'app.flash_dual_bank' in 'application[NUCLEO_F767ZI]'"