On an Android device that supports A/B slots, use a computer and the bootloader’s fastboot interface to check or select the slot for the next boot. Run fastboot getvar current-slot to check it; use fastboot set_active a or fastboot set_active b to select a slot only when your device’s instructions call for it. “Current slot” can also mean the slot used for the boot already in progress, which is a separate value.
What “current active slot” means
On supported A/B devices, Android keeps bootable partition sets identified by suffixes such as _a and _b. The boot-control interface distinguishes the slot used for the current boot from the slot selected to boot next. The fastboot variable current-slot reports the suffix selected for the next boot, not necessarily the slot that started the current session. The Android Open Source Project (AOSP) documents that the slot suffix is passed to Android through a device-tree node or a boot argument: A/B updates.
Before you run a slot command
- Confirm that your exact phone model supports A/B slots and exposes the relevant fastboot commands. Not every Android device does.
- Use a computer with the
fastbootcommand available, connect the phone, and enter its bootloader fastboot interface. The button combination and procedure vary by manufacturer; follow the instructions for your model. - Check for an in-progress system update before considering a slot change. AOSP’s implementation can refuse a change during a snapshot merge and warns that changing slots while a snapshot is applied may cancel the update.
- Do not treat slot switching as a generic repair step. Selecting a different slot does not repair its system image or guarantee that it can boot.
There is no universal Android Settings menu for changing the boot slot.
Check the slot selected for the next boot
- Boot the device into its manufacturer-supported bootloader fastboot interface and connect it to the computer.
- Run
fastboot getvar current-slot. - Read the returned suffix, typically
aorb. That is the slot selected for the next boot.
On supported bootloaders, fastboot getvar all displays the bootloader variables the device exposes; the available output varies by device. If current-slot is unsupported or the command fails, do not infer the slot from a guess. Verify A/B support and consult the manufacturer’s instructions.
Quick wins for a faster PC:
Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →#1 Best Overall
- Please note, this device does not support E-SIM; This 4G model is compatible with all GSM networks worldwide outside of the U.S. In the US, ONLY compatible with T-Mobile and their MVNO's (Metro and Standup). It will NOT work with other CDMA carriers, and it is also not compatible with their MVNO (Visible, Xfinity Mobile, US Mobile, Cricket Wireless, etc).
- Compatibility with certain third-party devices and accessibility accessories, including some hearing aids, may vary depending on manufacturer support, Bluetooth protocols, software compatibility, and regional firmware limitations. For additional hearing aid compatibility information, please refer to Samsung’s official support documentation.
- Camera: 50 MP, f/1.8, (wide), 1/2.76", 0.64µm, AF | 50 MP, f/1.8, (wide), 1/2.76", 0.64µm, AF | 2 MP, f/2.4, (macro). Battery: 5000 mAh, non-removable | A power adapter is NOT included.
Change the slot selected for the next boot
Only do this when you have a device-specific reason, have confirmed the model supports the command, and have checked that update processing is not in a state where switching could interfere with it.
- Enter the device’s bootloader fastboot interface using the manufacturer’s procedure.
- To select slot A, run
fastboot set_active a. To select slot B instead, runfastboot set_active b. Use the suffix supported by your device and the procedure you are following. - Reboot using the device-specific supported workflow.
AOSP defines fastboot set_active <slot> as selecting the A/B booting slot. The command changes which slot is selected for boot; it does not validate or restore the contents of that slot. If an update is underway or the command is rejected, stop and follow the phone maker’s update or recovery guidance rather than trying the other slot at random. See the AOSP fastboot implementation for its snapshot-state checks and warning behavior.
Quick Recap
Best Value
- Charger NOT Included, 6.7" Super AMOLED FHD+, 90Hz Refresh Rate, 385 ppi, 800 nits (HBM), 1080x2340px, 5000mAh Battery
- 128GB, 4GB RAM, microSDXC, Exynos 1330 (5nm), Octa-Core, Mali-G68 MP2 or Mali-G57 MC2 GPU
- Rear Camera: 50MP, f/1.8 (wide) + 5MP, f/2.2 (ultrawide) + 2MP, f/2.4 (macro), LED flash, panorama, HDR; Front Camera: 13MP, f/2.0, Android 14, up to 6 major Android upgrades, One UI 6.1
- 3G: HSDPA 850/900/1700(AWS)/1900/2100; 4G LTE: 1/2/3/4/5/7/12/13/14/20/25/26/28/29/30/38/39/40/41/48/66/71, 5G: 2/5/25/41/66/71/77/78 SA/NSA/Sub6/mmWave - Nano-SIM + eSIM
- US Model – Global Connectivity – Compatible with Most GSM Carriers like T-Mobile, AT&T, MetroPCS, etc. Will Also work with CDMA Carriers Such as Verizon, Straight Talk.
Rank #4
- YOUR CONTENT, SUPER SMOOTH: The ultra-clear 6.7" FHD+ Super AMOLED display of Galaxy A17 5G helps bring your content to life, whether you're scrolling through recipes or video chatting with loved ones.¹
- LIVE FAST. CHARGE FASTER: Focus more on the moment and less on your battery percentage with Galaxy A17 5G. Super Fast Charging powers up your battery so you can get back to life sooner.²
- MEMORIES MADE PICTURE PERFECT: Capture every angle in stunning clarity, from wide family photos to close-ups of friends, with the triple-lens camera on Galaxy A17 5G.
- NEED MORE STORAGE? WE HAVE YOU COVERED: With an improved 2TB of expandable storage, Galaxy A17 5G makes it easy to keep cherished photos, videos and important files readily accessible whenever you need them.³
- BUILT TO LAST: With an improved IP54 rating, Galaxy A17 5G is even more durable than before.⁴ It’s built to resist splashes and dust and comes with a stronger yet slimmer Gorilla Glass Victus front and Glass Fiber Reinforced Polymer back.
Rank #3
- Carrier: This phone is locked to Tracfone, which means this device can only be used on the Tracfone wireless network. Tracfone plan required, activating is easy, just 3 steps.
- DISPLAY: Immersive viewing on a 6.7-inch super-bright 120Hz display with powerful stereo speakers and Bass Boost for cinematic entertainment.
- CAMERA SYSTEM: Advanced 50MP Quad Pixel camera captures sharp, detailed photos and videos in any lighting condition
- PERFORMANCE: Lightning-fast 5G connectivity paired with a powerful processor and RAM Boost for smooth multitasking.
- BATTERY LIFE: Long-lasting 5000mAh battery with TurboPower charging technology delivers hours of power in minutes.
Rank #2
- YOUR CONTENT, SUPER SMOOTH: The ultra-clear 6.7" FHD+ Super AMOLED display of Galaxy A17 5G helps bring your content to life, whether you're scrolling through recipes or video chatting with loved ones.¹
- LIVE FAST. CHARGE FASTER: Focus more on the moment and less on your battery percentage with Galaxy A17 5G. Super Fast Charging powers up your battery so you can get back to life sooner.²
- MEMORIES MADE PICTURE PERFECT: Capture every angle in stunning clarity, from wide family photos to close-ups of friends, with the triple-lens camera on Galaxy A17 5G.
- NEED MORE STORAGE? WE HAVE YOU COVERED: With an improved 2TB of expandable storage, Galaxy A17 5G makes it easy to keep cherished photos, videos and important files readily accessible whenever you need them.³
- BUILT TO LAST: With an improved IP54 rating, Galaxy A17 5G is even more durable than before.⁴ It’s built to resist splashes and dust and comes with a stronger yet slimmer Gorilla Glass Victus front and Glass Fiber Reinforced Polymer back.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.
