
Samsung Galaxy Core2
The latest firmware for Samsung Galaxy Core2 (SM-G355HN) is G355HNXXU0AQD1 with Android 4.4.2 (KitKat), released on April 18, 2017 for 1 region (CSC). Every official firmware build for SM-G355HN, newest first: one row per build with all regions (CSC) that received it.
Each firmware build has its own page at https://samfirm.shop/build/{PDA}, where {PDA} is the build number from the list above. Example: https://samfirm.shop/build/G355HNXXU0AQD1
All 14 builds in our database run Android 4.4.2 (KitKat). The newest build, G355HNXXU0AQD1, was released on April 18, 2017. No new build has appeared for 115 months, so regular updates for this model have most likely ended.
Specifications of SM-G355H, a regional variant of the same device. Chipset and SIM lines are left out: they can differ by region.

SM-G355M

SM-G3509

SM-G3589W

SM-G357M

SM-G3568V
The newest firmware for SM-G355HN runs Android 4.4.2 (KitKat): build G355HNXXU0AQD1, released on April 18, 2017.
The latest build for SM-G355HN, G355HNXXU0AQD1, was released on April 18, 2017 (9 years ago).
SM-G355HN has had no new firmware for 115 months, so regular updates have most likely ended.
Yes, all firmware files for SM-G355HN are 100% official, original, and obtained directly from Samsung servers.
To flash SM-G355HN, 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-G355HN.