How to Fix 'Custom Binary Blocked by FRP Lock' on Samsung

By ErrorFix · Updated October 22, 2026 · 6 min read

What 'Custom binary blocked by FRP Lock' means

When a Samsung phone shows "Custom binary blocked by FRP Lock" — usually in red or orange text on the Download Mode screen or a black boot screen — it isn't a random glitch. It is a deliberate security stop. The phone's bootloader noticed that the software it is being asked to start didn't come from Samsung (a "custom binary"), and because Factory Reset Protection, the anti-theft lock that ties the phone to a Google account, is active, the phone refuses to boot at all.

Most people land here after one of three things: they tried to root the phone or install a custom recovery like TWRP, they flashed a firmware file that didn't match their exact model or region, or they bought a used phone that a previous owner had already modified. Sometimes the chain is subtler — an interrupted unofficial flash can leave behind a partially written custom binary, and the next reboot trips the FRP check even though nothing was done intentionally.

The important thing to understand is that you can't tap your way out of this. There is no settings menu, no recovery-mode factory reset that helps, and no button combination that skips it. The FRP lock and the custom-binary check live below Android itself, in the bootloader. The only way back is to replace the unofficial software with Samsung's own official firmware using Odin, Samsung's PC flashing tool — and then satisfy the FRP lock with the original Google account.

Common causes

• Custom firmware or recovery flashed with FRP active: root packages, custom ROMs, or TWRP installed while the Google-account lock was still on — the classic trigger.
• Wrong firmware for your model: flashing a file built for a different variant or region counts as a custom binary to the bootloader.
• Interrupted unofficial flash: a cable that came loose or a PC that crashed mid-flash leaves a partial custom binary behind.
• A previously modified used phone: the seller rooted it or flashed it, FRP was never cleared, and the lock surfaced on your first reboot.
• FRP tripped after unofficial repair: a motherboard swap or unofficial service can leave the phone in a state where the lock and the binary check collide.

How to fix it — step by step

Work through these in order. The heart of the fix is one clean Odin flash of official firmware, but the preparation steps are what keep that flash from failing.

1. Confirm your phone's exact model number. The FRP-locked download screen usually lists it (something like SM-G991B or SM-A536U). Check the original box, the back panel under the battery cover, or the sticker under the SIM tray if the screen doesn't show it. Firmware is model-specific — flashing files meant for a different variant is the fastest way to turn a soft problem into a hard brick.
2. Download the official stock firmware for your exact model and region. Get it from Samsung's own firmware channels or a well-known firmware repository that hosts untouched Samsung images. Match the model number character for character and pick your country code (CSC). Extract the ZIP so you have the separate BL, AP, CP, and CSC files ready.
3. Set up the PC side: Samsung USB drivers, a good cable, and Odin. Install the official Samsung USB driver package on your Windows PC, restart the computer, and use a quality data cable plugged into a rear USB port — cheap charge-only cables cause most mid-flash failures. Run the Odin flashing tool as administrator.
4. Boot the phone into Download Mode and connect it. Power the phone off completely. On older models, hold Volume Down + Home + Power; on newer models without a Home button, plug the USB cable into the PC and hold Volume Down + Volume Up together, then press Volume Up when the warning screen appears. Connect the phone — Odin's ID:COM box should light up blue.
5. Flash the stock firmware in Odin and wait for PASS. Load the BL file into the BL slot, AP into AP, CP into CP, and the full CSC file (not HOME_CSC) into CSC — the full CSC performs the clean wipe these situations need. Make sure only Auto Reboot and F. Reset Time are checked, then click Start. Do not touch the cable or close Odin until the box shows PASS and the phone reboots on its own, which can take five to ten minutes.
6. Complete setup with the original Google account and prevent a repeat. After the flash, Factory Reset Protection will ask for the Google account that was previously synced to this phone — sign in with those credentials to clear the lock. Once you're in, go to Settings > Accounts and backup > Manage accounts and remove the Google account before any future unofficial flashing, and keep OEM unlocking disabled unless you know exactly what it does.

Did this fix it? Quick checklist

• The phone boots to the Samsung setup wizard instead of the FRP-blocked screen
• Odin showed PASS and the phone rebooted on its own (never unplug mid-flash)
• You can complete setup by signing in with the previously synced Google account
• Future-proofed: Google account removed and OEM unlocking left off before any unofficial flashing

If Odin fails instead of showing PASS, stop and diagnose before retrying: confirm the model number letter-for-letter against the firmware, try a different cable and a rear USB port, reinstall the Samsung USB drivers, and make sure you're using the full CSC file rather than HOME_CSC. Repeated failures with the right files on the right model usually point to a damaged USB port or a deeper hardware problem, and at that point a Samsung service center is the safer bet than another flash attempt.