
Samsung Galaxy Win Pro
Every official firmware build for SM-G3819, newest first: one row per build with all regions (CSC) that received it.

SM-G3819D

SM-G388F

SM-G386W

SM-G3858

SM-G390W
You can find the firmware on the model: SM-G3819 page.
Yes, all firmware files for SM-G3819 are 100% official, original, and obtained directly from Samsung servers.
To flash SM-G3819, 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 SM-G3819.