Here is how to flash Samsung phone firmware with Odin: download the official firmware for your exact model, put the phone in Download mode, load the BL, AP, CP and CSC files into Odin on a Windows PC, and press Start. The whole job takes a few minutes, but a full flash with the normal CSC file erases everything on the phone. This 2026 guide covers the requirements, the exact steps, the new Download mode change on recent Galaxy phones, and how to fix common Odin errors.

Before You Start: Do You Need Odin?

Odin is Samsung’s internal flashing tool for Windows. It talks to Galaxy phones in Download mode and writes full firmware packages to them. There is no record of Samsung releasing Odin to the public, so the copies people use are believed to be leaked builds.

Use Odin when the phone is stuck in a boot loop, a software update failed, or you need to reinstall the official firmware. For a normal update, the official options are simpler and safer:

  • Settings > Software update > Download and install on the phone.
  • Samsung’s Smart Switch for PC. If an update fails, Smart Switch has MORE > Emergency Software Recovery and Initialization, as described in Samsung’s recovery guide.

Requirements

  • A Windows PC and a good USB data cable. Not every USB cable can transfer data; some only charge.
  • Samsung USB driver. Samsung’s developer site lists version 1.9.5.0 (May 2026). See also our Samsung USB driver page.
  • Odin. The current stable Windows build is Odin3 v3.14.1. A v3.14.4 also circulates, but its origin is disputed, and because Samsung never released Odin officially, no version can be checked against an official copy. Get it from our Samsung Odin downloader page.
  • Firmware for your exact model. Find the model number in Settings > About phone (for example SM-S921B). Use firmware made for that exact model number only.
  • A backup. Flashing with the normal CSC file wipes all apps, photos and files.
  • Your Google Account password. After a wipe, Android asks for the Google Account that was on the phone. Google advises checking that you know this password before any reset.
  • Battery charge. Charge the phone well before you start. Google recommends at least 70% before a factory reset.

Where to Get Official Firmware

Every firmware has a build number, such as S921BXXU6EZIF (a Galaxy S24 build). Use a downloader that fetches the package from Samsung’s servers, for example the open-source Bifrost (you enter your model and region code). Avoid firmware re-uploaded to file-sharing sites, because you cannot check that it is unmodified.

Check the Bootloader Revision

The fifth character from the right in a Samsung build number is the bootloader revision. In S921BXXU6EZIF, it is 6. Odin will not flash firmware with a lower bootloader revision than the one already on the phone. Compare it with the build number in Settings > About phone > Software information and choose firmware with the same or a higher number.

What the Firmware Files Do

Odin slot File Contents
BL BL_….tar.md5 Bootloader
AP AP_….tar.md5 Android system partitions
CP CP_….tar.md5 Modem (radio) firmware
CSC CSC_….tar.md5 Region and carrier settings. Wipes all data.
CSC HOME_CSC_….tar.md5 Region and carrier settings. Meant to keep your data.

Use either CSC or HOME_CSC in the CSC slot, never both. Old Galaxy models use a single file that goes in AP.

Step 1: Put the Phone in Download Mode

  1. Switch the phone off completely.
  2. On current Galaxy phones without a Home button, press and hold Volume Up + Volume Down, then plug in the USB cable that is already connected to the PC.
  3. When the blue warning screen appears, release the buttons and press Volume Up to continue. Volume Down cancels.

Older models use different keys. Phones with a Home button use Volume Down + Home + Power, and models with a Bixby key use Volume Down + Bixby + Power.

New in 2026: Maintenance Mode on One UI 8.5 and Later

In March 2026, Android Authority reported that on the Galaxy S26 series and Galaxy Z Fold7 with One UI 8.5, the key combination only showed a plain blue screen. The report was later updated: Download mode and Odin still work, but you must turn on Maintenance mode first. Community guides say the same applies on One UI 9 and that it may differ by region. Samsung has not explained the change.

If your phone only shows a blue screen, try this:

  1. With the phone booted normally, open Settings > Device care > Maintenance mode and tap Turn on. Samsung’s Maintenance mode guide explains the prompts.
  2. After the phone restarts in Maintenance mode, switch it off and use the Download mode keys again.

Some community guides also say to switch off the Create log option on the Maintenance mode screen first. This method only works if the phone can still boot. If it cannot, try Smart Switch emergency recovery or a Samsung service centre.

Step 2: Flash the Firmware with Odin

  1. Extract the firmware ZIP to a folder. You should see the BL, AP, CP, CSC and HOME_CSC files.
  2. Close Smart Switch (or the older Kies) if it is open. Odin guides recommend closing it before you flash.
  3. Extract the Odin ZIP, right-click the Odin3 program and choose Run as administrator.
  4. Connect the phone in Download mode. The ID:COM box turns coloured and the log shows Added!!. If it does not, see the troubleshooting section below.
  5. Click BL, AP, CP and CSC and load the matching file into each. Choose HOME_CSC to try to keep your data, or CSC for a clean flash.
  6. In the Options tab, keep Auto Reboot and F. Reset Time ticked. Do not tick Re-Partition and do not use the PIT tab.
  7. Click Start. Do not touch the cable or the phone until Odin finishes.
  8. When the box shows PASS!, the phone restarts by itself. It may restart more than once before it reaches the setup screen.

Troubleshooting Odin Errors

No “Added!!” Message

  • Install or reinstall the Samsung USB driver, then restart the PC.
  • Try another USB port and a different data cable.
  • Make sure the phone is really in Download mode, not recovery mode or the blue warning screen.

FAIL! or “SW REV CHECK FAIL”

This message means the firmware has a lower bootloader revision than the phone (“DEVICE” is higher than “BINARY”). Download firmware for the same model with the same or a higher revision. Other FAIL causes are firmware for the wrong model, an old Odin build or a loose USB connection.

Boot Loop After a HOME_CSC Flash

If the phone keeps restarting after a HOME_CSC flash, guides recommend a clean flash with the normal CSC file. That erases the phone, so this is where your backup matters.

Does Flashing Trip Knox?

Official Samsung firmware for your model does not. Samsung’s Knox documentation says the warranty bit is tripped by a non-Knox kernel or by rooting, and once tripped it cannot be reset. After that, Secure Folder, Samsung Pay and other Knox-based features stop working. Stick to signed official firmware if you want to keep them.

Related Guides

FAQ

Does flashing with Odin erase my data?

With the normal CSC file, yes: the phone is wiped. HOME_CSC is meant to keep your apps and files, but it is not guaranteed, so always back up first.

Can I downgrade Samsung firmware with Odin?

Only to firmware with the same bootloader revision as your phone. Odin refuses firmware with a lower revision and shows SW REV CHECK FAIL. Downgrading also usually needs the normal CSC file, which wipes the phone.

Which Odin version should I use?

Use a 3.14 build, such as v3.14.1, for current Galaxy phones. Older builds were made for much older Android versions. Odin3 runs on Windows; there is also a Linux version called Odin4.

Do I need Odin to install One UI 9?

No. Eligible phones get One UI 9 through Settings > Software update or Smart Switch. Odin is only needed when the normal update path does not work.

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