A new firmware update is being rolled out to two Samsung devices- Galaxy Ace 4 Neo Duos and Galaxy Tab E. The update comes with latest monthly security patch and is on the roll out as we speak.
Samsung has been quite active these days seeding out the March security patch to its devices one by one. It has pushed the update to a couple of devices in the past week including Galaxy J5 2016, J2 Prime, Galaxy C5, Galaxy A7 2017, Grand Prime Plus, Galaxy A9 (in China) and Tab A 10.1 (2016).
Meanwhile, users of Galaxy Ace 4 Neo Duos have reported receiving the March security patch as build number G318MZDXS0AQC1. The same monthly update is hitting Galaxy Tab E units as build number G532GDDU1AQC2.
As is the case with monthly security update, it is being rolled out as OTA and in a phased manner. Therefore, it may take some time to reach you. If waiting is not your thing, you can check for it manually by heading to Settings > About device > System updates. Ensure that your device is sufficiently charged and connected to a WiFi network before initiating the download.