[Galaxy S 4 Q&A, Help & Troubleshooting] MisterXtm:
I reverted to XXUFNB8 (modem) and flashed it successfully, just to get some new errors:

First:

03-07 11:41:25.940 E/WifiHW (839): Supplicant not running, cannot connect

03-07 11:41:26.941 E/WifiHW (839): Supplicant not running, cannot connect

03-07 11:41:27.932 E/WifiHW (839): Supplicant not running, cannot connect

03-07 11:41:28.002 D/WifiDisplayAdapter(839): getWifiDisplayStatusLocked: result=WifiDisplayStatus{featureState=1, scanState=0, activeDisplayState=0, activeDisplay=null, displays=[], sessionInfo=WifiDisplaySessionInfo: Client/Owner: Client GroupId: Passphrase: SessionId: 0 IP Address: , connectedState=-1, networkQoS=0}

03-07 11:41:28.123 D/WifiDisplayAdapter(839): getWifiDisplayStatusLocked: result=WifiDisplayStatus{featureState=1, scanState=0, activeDisplayState=0, activeDisplay=null, displays=[], sessionInfo=WifiDisplaySessionInfo: Client/Owner: Client GroupId: Passphrase: SessionId: 0 IP Address: , connectedState=-1, networkQoS=0}

03-07 11:41:28.243 D/WifiDisplayAdapter(839): getWifiDisplayStatusLocked: result=WifiDisplayStatus{featureState=1, scanState=0, activeDisplayState=0, activeDisplay=null, displays=[], sessionInfo=WifiDisplaySessionInfo: Client/Owner: Client GroupId: Passphrase: SessionId: 0 IP Address: , connectedState=-1, networkQoS=0}

03-07 11:41:28.933 E/WifiHW (839): Supplicant not running, cannot connect

03-07 11:41:28.933 E/WifiMonitor(839): startMonitoring(wlan0) failed!

03-07 11:41:28.933 E/WifiStateMachine(839): Failed to setup control channel, restart supplicant

03-07 11:41:29.134 D/WifiHW (839): Unable to unload driver module "dhd": Device or resource busy

03-07 11:41:29.134 E/WifiHW (839): ##################### set firmware type 0 #####################

03-07 11:41:29.134 E/WifiHW (839): is_wifi_driver_loaded() is true !!!

03-07 11:41:29.134 I/WifiHW (266): wifi_change_fw_path(): fwpath = /system/etc/wifi/bcmdhd_sta.bin

03-07 11:41:29.194 E/WifiStateMachine(839): Unable to change interface settings: java.lang.IllegalStateException: command '24 interface setcfg wlan0 0.0.0.0 0 down' failed with '400 24 Failed to set address (No such device)'

03-07 11:41:29.194 E/WifiHW (839): supplicant_name : p2p_supplicant

03-07 11:41:29.214 D/WifiMonitor(839): startMonitoring(wlan0) with mConnected = false

Then again:

03-07 11:41:44.228 E/WifiHW (839): Supplicant not running, cannot connect

03-07 11:41:44.228 E/WifiMonitor(839): startMonitoring(wlan0) failed!

03-07 11:41:44.228 E/WifiStateMachine(839): Failed to setup control channel, restart supplicant

03-07 11:41:44.428 D/WifiHW (839): Unable to unload driver module "dhd": No such file or directory

03-07 11:41:44.428 E/WifiHW (839): ##################### set firmware type 0 #####################

03-07 11:41:44.428 E/WifiHW (839): Cannot open "/data/.cid.info": No such file or directory

03-07 11:41:44.428 E/WifiHW (839): ==========[WIFI] Station firmware load ===========

03-07 11:41:47.912 D/Finsky (5732): [1] CheckWifiAndAutoUpdate.cancelCheck: Cancelling auto-update wifi check.

03-07 11:41:48.913 D/Finsky (5732): [1] CheckWifiAndAutoUpdate.scheduleCheck: Scheduling auto-update wifi check.

03-07 11:41:59.483 E/WifiHW (839): return of insmod : ret = -1, No such device

03-07 11:41:59.483 E/WifiStateMachine(839): Failed to load driver

03-07 11:41:59.483 E/WifiStateMachine(839): sendErrorBroadcast code:10