Flashing new firmware sounds like starting over, so it is natural to worry about what else gets wiped in the process. Photos and apps are the usual concern, but for a growing number of Galaxy owners the real question is the eSIM. If your number lives on an embedded SIM rather than a plastic card, will a flash delete it? The short answer is no, not with official firmware flashed the normal way, but there are a few details worth knowing before you start.
Where an eSIM actually lives
An eSIM is not a file sitting in Android's storage. It lives on a dedicated, tamper-resistant chip inside the phone, separate from the system partition that firmware replaces. When you flash a Samsung firmware package, Odin rewrites the system, modem, and bootloader partitions, but it does not touch that secure chip. Your eSIM profiles stay where they are, in the same way a physical SIM card stays in its tray during a flash.
That separation is deliberate. Carriers and phone makers designed eSIM storage to survive software changes, because losing your mobile number every time the software was updated would make the whole idea unusable. A firmware update, whether over the air or flashed manually, is a software change, not a hardware reset.
What a flash does change
A flash does rewrite the modem software, which is the part of the phone that talks to mobile networks. After flashing, the phone may need a moment to re-register on the network, and in rare cases it may ask you to confirm your mobile plan or re-download carrier settings. That is a network handshake, not a deletion. Your eSIM profile is still there; the phone is simply re-establishing its connection with the carrier's network using it.
The one setting that can genuinely change is the CSC, or region code, if you flash firmware for a different region. A different CSC can change which carrier features are enabled, such as Wi-Fi calling or VoLTE, because those features are switched on per region. It does not delete the eSIM, but it can change how the phone behaves on the network, so flashing a different region's firmware deserves a second thought even when the eSIM itself is safe.
The case where an eSIM can be lost
There is one real exception, and it is not the flash itself. It is the wipe that sometimes goes with it. If you choose a full wipe in Odin, or perform a factory reset as part of the process, some phones offer an option to erase eSIMs as well. That option is usually presented as a separate checkbox, and it is off by default on most Galaxy models, but it is worth reading the screen carefully before confirming any reset.
A factory reset from within Android's settings has the same separate eSIM option. If you ever see a prompt asking whether to erase eSIMs, and you do not intend to give the phone away or change carriers, leave that box unchecked. The flash alone will not check it for you.
After the flash: what to check
Once the phone boots after a flash, the checks are quick. Open Settings, then Connections, then SIM manager, and confirm your eSIM profile is listed. If mobile data works and calls connect, everything is as it should be. If the phone shows no service for more than a few minutes, restarting it once usually prompts the network registration to complete. If the profile is genuinely missing, your carrier can usually reissue the eSIM by QR code, though that is a hassle worth avoiding by checking the wipe options first.
So the rule is simple. Flashing official Samsung firmware does not delete your eSIM, because the eSIM lives outside the partitions a flash rewrites. The risk only appears when a wipe or reset explicitly asks about eSIMs, and that is a choice you control. Read that one screen, and your number survives the flash intact.
You can find official stock firmware for your Galaxy model and region at SamFware, with step-by-step Odin guides if you ever need to flash manually. SamFware hosts free Samsung firmware downloads, organised by model and CSC, so you can check exactly which version your phone should be running.
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