
Samsung Galaxy S4 (LTE-A/S800)
The latest firmware for Samsung Galaxy S4 (LTE-A/S800) (GT-I9506) is I9506XXUDRB1 with Android 5.0.1 (Lollipop), released on February 14, 2018 for 9 regions (CSC). Every official firmware build for GT-I9506, newest first: one row per build with all regions (CSC) that received it.
GT-I9506 started on Android 4 and has received 1 major Android upgrade; it now runs Android 5.0.1 (Lollipop). The newest build, I9506XXUDRB1, was released on February 14, 2018. No new build has appeared for 105 months, so regular updates for this model have most likely ended.
Box codes of GT-I9506 for different colors and markets. Firmware is chosen by the model code GT-I9506 and your region (CSC), not by the SKU.
The newest firmware for GT-I9506 runs Android 5.0.1 (Lollipop): build I9506XXUDRB1, released on February 14, 2018.
The latest build for GT-I9506, I9506XXUDRB1, was released on February 14, 2018 (8 years ago).
GT-I9506 has had no new firmware for 105 months, so regular updates have most likely ended.
Yes, all firmware files for GT-I9506 are 100% official, original, and obtained directly from Samsung servers.
To flash GT-I9506, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing GT-I9506.