Odin doesn’t explain much when something goes wrong. You get a red FAIL box, a couple of lines in the log, and that’s it.
The good news is that most Odin failures come down to the same handful of causes. On this page, I’ll go through each common error, what it actually means, and how to fix it.
I copied the log messages below straight from the Odin3 v3.14.4 program files, so they should match what you see in your log word for word. Spelling mistakes included.
First, read the Odin log
The Log tab on the left side of Odin tells you exactly where things stopped. A normal flash goes through these lines, roughly in this order:
| Log line | What Odin is doing |
|---|---|
| Added!! | The phone is connected and Odin can see it. |
| Odin engine v(ID:…).. | The flash has started. |
| File analysis.. | Odin is reading the firmware files you loaded. |
| SetupConnection.. | Odin is opening a session with the phone. |
| Initialzation.. | The phone is getting ready to receive data. Yes, Odin spells it that way. |
| Get PIT for mapping.. | Odin reads the phone’s partition table. |
| Firmware update start.. | Writing is about to begin. |
| NAND Write Start!! | Odin is writing the firmware to the phone. |
| RQT_CLOSE !! and RES OK !! | Writing is done and the phone accepted it. |
| All threads completed. (succeed 1 / failed 0) | The flash worked. The box at the top turns green and says PASS. |
When a flash fails, the last line says “All threads completed. (succeed 0 / failed 1)”. That line alone tells you nothing. The line right above it is the one you need, so find it and match it with the sections below.
One more tip. Always look at the phone screen too. When the phone rejects a file, it often prints a red message at the top of the Download Mode screen that explains more than Odin does.
Odin doesn’t detect the phone
No ID:COM and no “Added!!” message
This is the most common problem, and it happens before you even press Start. Odin simply can’t see the phone.
- Make sure the phone is in Download Mode, not just switched off or charging.
- Install the Samsung USB Driver and restart the PC.
- Swap the cable for one that you know can transfer data.
- Use a USB port directly on the PC, not a hub.
- Close Smart Switch and run Odin as administrator.
Can’t open the serial(COM) port.
Odin sees the port but can’t use it. Something else usually has it open, like Smart Switch, a second Odin window, or a stuck connection from an earlier attempt.
Close every other phone tool, unplug the cable, put the phone back into Download Mode, and connect it again. If the message keeps coming back, reinstall the Samsung USB Driver.
Stuck at SetupConnection.. or Initialzation..
Odin found the phone but the two can’t finish talking to each other. In my experience, this is almost always the cable or the USB port.
Close Odin, force the phone out of Download Mode by holding Volume Down and Power, and start again with a different cable and port. Also make sure you’re on Odin3 v3.14.4, because very old Odin builds don’t get along with newer phones.
FAIL messages in the Odin log
FAIL! Model mismatch fail
The firmware you loaded was built for a different model. Older Odin versions show the same error as “Model dismatch fail”.
Check your exact model number. You’ll find it in Settings > About phone, or on the Download Mode screen next to the product name. Then download firmware for that exact number. A Galaxy S24 Ultra sold in Europe (SM-S928B) and one sold in the US (SM-S928U) need different firmware, even though they’re the same phone.
FAIL! (Auth)
The phone checked the signature on one of the files and refused it. There are three usual reasons:
- The firmware has an older bootloader version than the one already on your phone. Look at the phone screen for SW REV. CHECK FAIL, covered further down.
- You’re flashing a custom or modified file, like TWRP or a patched boot image, on a phone with a locked bootloader.
- The firmware is for a different model or a different chipset variant.
Flash official firmware for your exact model with the same or a newer bootloader version, and this error goes away.
There is no PIT partition. / Re-Partition operation failed.
Odin tried to change the phone’s partition layout and couldn’t. This almost always happens because Re-Partition was ticked in the Options tab, or a PIT file from another model was loaded.
Untick Re-Partition, clear the Pit tab, and flash the full firmware package again with the CSC file included. Odin even warns about this. When you load a CSC file, it says “Your device will be changed with the pit in CSC file.” So the CSC already carries the right PIT for your phone.
Complete(Write) operation failed. / FAIL! (Write)
Odin started writing, but the transfer broke halfway. A loose cable, a flaky USB port, or a PC going to sleep can all do this.
Don’t panic. The phone usually still boots into Download Mode. Switch to a different cable and port, turn off sleep mode on the PC, and flash the same firmware again.
md5 error! Binary is invalid
The firmware file is damaged or incomplete. Odin checks the MD5 hash of .tar.md5 files before it flashes anything, and this file didn’t match.
Download the firmware again and extract the ZIP again. Don’t rename .tar.md5 files, and make sure the download actually finished before you open it.
FAIL! LZ4 is invalid / FAIL! SHA256 is invalid
Same idea as the MD5 error, but for the compressed .lz4 images inside newer firmware. One of them is corrupted. Download the firmware again.
FAIL! (Size)
A file in the firmware is bigger than the space the phone has for it. You’re almost certainly flashing firmware meant for a different model or variant. Double-check the model number and download the matching package.
FAIL! (Ext4)
Odin couldn’t process one of the system images. A broken download is the usual cause, and an outdated Odin version is the second. Download the firmware again and use Odin3 v3.14.4.
Errors on the phone screen
These show up in red at the top of the Download Mode screen, usually at the same moment Odin shows FAIL. The exact wording changes a little between models and bootloader versions.
SW REV. CHECK FAIL
You’ll see something like DEVICE: 5, BINARY: 4. It means the firmware you’re flashing has a lower bootloader version (4) than the one already on your phone (5). Samsung blocks that kind of downgrade, and there’s no way around it.
You can find the bootloader version in the firmware build number. It’s the fifth character from the end. In S928BXXU4BXK1, for example, it’s the 4. Download firmware with the same or a higher number and flash that instead. I break down every part of the build number in my Samsung firmware files guide.
Custom binary blocked by FRP lock
You tried to flash a custom file while Factory Reset Protection is active. FRP is turned on whenever a Google account is signed in on the phone.
Flash the official firmware to get the phone booting again. If you do want to flash custom files later, unlock the bootloader first. That needs OEM unlocking enabled in Developer options.
Only official released binaries are allowed to be flashed
The bootloader is locked, so the phone only accepts files signed by Samsung. This is the phone protecting itself, not a bug in Odin. Stick to official firmware for your model.
An error has occurred while updating the device software
You get this screen when a flash stopped halfway. It tells you to use Smart Switch emergency recovery, but you don’t have to.
Hold the Download Mode buttons for your model to get back into Download Mode, then flash the full, correct firmware with Odin again. In most cases, the phone boots normally afterward.
Odin freezes, crashes or won’t open
Odin stops responding while loading AP
The AP file on a recent Galaxy is several gigabytes, and Odin checks it before it lets you continue. Windows may show Not Responding during that time. Give it a few minutes. It’s working.
Odin sits on NAND Write Start!! for a long time
This is normal too. Writing the system image takes a while, especially on big firmware packages. Wait at least 15 minutes, and never unplug the cable while the progress bar is still moving.
Odin won’t open or closes right away
Usually you ran the exe from inside the ZIP, or a file went missing during extraction. Odin needs its DLL and settings file sitting next to it. Extract the whole ZIP into its own folder and run the exe from there. If SmartScreen blocks it, check the SHA-256 on the download page first, then click More info and Run anyway.
Old Odin with new firmware
Current Samsung firmware uses .lz4 compressed images. Odin3 v3.12.7 and older can’t read them, so the flash fails no matter what else you do. Use Odin3 v3.13.1 or newer. I recommend v3.14.4.
Odin error questions
What does “All threads completed. (succeed 0 / failed 1)” mean?
It means Odin tried to flash one phone and it failed. It’s a summary, not the reason. The real cause is in the line just above it in the Log tab.
Will an Odin FAIL brick my phone?
Usually not. Many errors, like Model mismatch and Auth, stop the flash before much is written. Even if it fails halfway, Download Mode almost always still works, and flashing the correct firmware brings the phone back.
Should I tick Re-Partition to fix an Odin error?
No. Re-Partition rewrites the partition layout and should only be used with the exact PIT file for your model, when a repair guide specifically asks for it. For a normal flash, leave it off.
Can I downgrade my Samsung firmware with Odin?
Only if the older firmware has the same bootloader version as your phone. If the bootloader number is lower, the phone shows SW REV. CHECK FAIL and refuses the flash.
Will a different Odin version fix my error?
Rarely. If you’re on a very old build, move to v3.14.4. If v3.14.4 misbehaves on a particular PC, v3.14.1 is a good fallback. But errors like Auth, Model mismatch and SW REV. CHECK FAIL come from the phone and the firmware, and no Odin version gets around them.
Odin says PASS, but my phone is stuck on the boot logo. What now?
Give the first boot up to 10 minutes. If it still doesn’t start, boot into recovery mode and do a factory reset. This happens most often after flashing HOME_CSC over a very different firmware version. Keep in mind that a factory reset erases your data. Read my firmware files guide to see how CSC and HOME_CSC differ.
Before you try again: Go back through the Odin tutorial and check the model, CSC, bootloader version and file names. Most repeat failures happen because one of these was never fixed.
If your error isn’t listed here, send me a message through the contact page. Tell me your Galaxy model number, the full firmware file name, and the last few lines of the Odin log. A screenshot of the log works too.