LG BU40N 1.00 firmware is widely regarded by enthusiasts as the "gold standard" for UHD-friendly optical drives. It is primarily used to cross-flash other slim LG and Archgon drives to enable LibreDrive
“The LG BU40N on firmware version 1.00 is the most coveted revision for 4K Blu-ray ripping because LG removed UHD support after 1.02. If your drive is on 1.00 already, do not let Windows Update or LG’s tool upgrade it. If you are on newer firmware, you can force-flash back to 1.00 using a patched tool – but you need the correct BU40N_1.00.bin file from the MakeMKV forum. Keep in mind that stock 1.00 has a lower read speed cap; an alternative is to flash to 1.00-MK or 1.02-MK which fixes speed while retaining LibreDrive.”
Burn Quality Stability: Some users have reported that later firmwares (1.03 or 1.04), even when modified, introduce bugs when burning 100GB BD-XL triple-layer discs. Version 1.00 remains the most stable for those who still burn physical backups. Comparisons with Newer Versions Firmware 1.00 Firmware 1.03/1.04 MK UHD Ripping MakeMKV Support Fully Supported Fully Supported DVDFab Support Generally Unsupported Read Speed Standard (up to 6x) Slightly Faster in some cases Downgrade Protection Sometimes Present The Flashing Dilemma: Downgrading to 1.00 bu40n 1.00 firmware
While 1.00 is a stable baseline, users encountering errors are often advised to seek official updates if they exist. LG occasionally releases updates (e.g., 1.01, 1.02) to add support for new 128GB BDXL media or to fix bugs where the drive fails to recognize specific disc brands.
LibreDrive Support: When flashed correctly, version 1.00 allows MakeMKV to access the drive via "LibreDrive" mode, bypassing the drive's internal AACS revocation list to read 4K UHD discs directly. LG BU40N 1
| Property | Value |
|----------|-------|
| Drive platform | MT1959 (Supports LibreDrive) |
| Bus encryption | Present but removable via firmware |
| Sleep bug | No (introduced in later firmware) |
| UHD out-of-box | Yes (if manufactured before mid-2018) |
Note: You will not find it on LG’s official support site – they only host newer versions. If you are on newer firmware, you can force-flash back to 1
Popular external drive; flashing to BU40N 1.00 unlocks 4K reading. SDFtool Flasher LG BP50NB40
Disclaimer: Flashing firmware carries a risk of bricking your drive (making it unusable). Proceed at your own risk. This guide assumes you have a BU40N with SVC Code NS50 (check the sticker on the drive).