X420AS20g: AT&T LG K40 Firmware Update with Dec. Security Patch

AT&T LG K40 (LMX420AS) Firmware Update X420AS20g – Android 10 with December 2020 Security Patch.

The LG K40 LMX420AS (LM-X420AS, X420AS) is now receiving a new firmware update from AT&T.

AT&T is now pushing a security patch update to its LG K40 LMX420AS (LM-X420AS, X420AS) smartphone to version X420AS20g.

The update weighs in at  135MB and includes the December 2020 Android security patches.

Last October, The AT&TLG K40 LMX420AS (LM-X420AS, X420AS) received the Android 10 OS Update which brings the device’s software version to X420AS20f!

  • Android version: 10
  • Software version: X420AS20f
  • File size: 129MB

AT&T LG K40 (LMX420AS) Firmware Update X420AS20g

  • Release date: December 14, 2020
  • Android version:10
  • Device: LG K40
  • Model: LMX420AS,LM-X420AS, X420AS
  • Security patch level (SPL): December 1, 2020
  • Build number: QKQ1.200614.002
  • Software version: X420AS20g
  • File size: 135MB
  • ChangeLog: Decmeber 2020 security Patch

The Update is now available via OTA,  you can manually check for the update by going into Settings > General tab > Update center > System update > Check for the update!

For your information, the AT&T LG K40 (LMX420AS) does not support software update through LG Bridge.

FAQ: Where I can download the AT&T LG K40 Firmware?

There is no way to download AT&T LG K40 lmx420as KDZ Firmware from the LG server because AT&T LG phones support FOTA Update only.

As AT&T hosts the firmware on its own server, You can ask other LG K40 users to capture the OTA Update download URL.


Need to download AT&T LG K40 LMX420AS, LM-X420AS, x420AS Drivers? You can get it here.

AT&T LG K40 User Manual / Guide

Source: https://www.att.com/device-support/article/wireless/KM1371725/LG/LMX420AS/