[[["容易理解","easyToUnderstand","thumb-up"],["確實解決了我的問題","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["缺少我需要的資訊","missingTheInformationINeed","thumb-down"],["過於複雜/步驟過多","tooComplicatedTooManySteps","thumb-down"],["過時","outOfDate","thumb-down"],["翻譯問題","translationIssue","thumb-down"],["示例/程式碼問題","samplesCodeIssue","thumb-down"],["其他","otherDown","thumb-down"]],["上次更新時間：2025-07-27 (世界標準時間)。"],[],[],null,["# Flash with Fastboot\n\nThis page provides details for flashing Android builds onto devices using the\n*fastboot* and *adb* tools. Adb lets you connect your\ndevelopment workstation directly to your Android-powered device and\nperform a variety of operations. Fastboot lets you install (flash) Android\nand interact with the device's bootloader so you can test your OS and app\nchanges. For additional information on how adb works, with emphasis on app\ndevelopment, see\n[Android Studio's Android Debug Bridge (adb) page](https://developer.android.com/studio/command-line/adb).\nIf you want details on the code for adb, see the adb\n[README](https://cs.android.com/android/platform/superproject/+/android-latest-release:packages/modules/adb/README.md).\n| **Note:** Google provides an additional flash tool, called [*Android Flash Tool*](/docs/setup/test/flash), that is intended for use only with prebuilt builds.\n| **Note:** Fastboot is also the name of a bootloader module and mode.\n\nVerify that you have fastboot and adb\n-------------------------------------\n\nWhen you build Android, adb and fastboot is built by default. To confirm\nthe availability of adb and fastboot, run the following commands: \n\n adb --version\n fastboot --version\n\nIf you see version numbers, you have fastboot and adb installed. If you\ndon't see version numbers, ensure you\n[built Android](/docs/setup/build/building).\nsuccessfully. Continue to\n[Enable your USB connection](#enable-usb).\n\nEnable your USB connection\n--------------------------\n\nBefore running Android on a device, you must enable your USB connection:\n\n1. Enable OEM unlocking and USB debugging in the developer options:\n\n 1. In the Settings app, tap **About phone**.\n 2. Tap **Build number** seven times.\n 3. When you see the message **You are now a developer!** , tap **\\\u003c-**.\n 4. Tap **System** , then tap **Developer options**.\n 5. Enable **OEM unlocking** and **USB debugging** . If OEM unlocking is unavailable, connect to the internet so the device can check in. If that still doesn't work, you can force a check in: In the Dialer app, enter **\\*#\\*#CHECKIN#\\*#\\*** (\\*#\\*#2432546#\\*#\\*) (no SIM required). After entering the number (no need to press call), the text disappears and a success notification appears.\n\n If OEM unlocking remains unavailable, your device might be SIM locked by\n your carrier and the bootloader can't be unlocked.\n2. Connect your device to a USB port on your workstation.\n\nBoot into Fastboot mode\n-----------------------\n\nBefore Android can be flashed to a device, a device must be in Fastboot mode.\nThere are two ways to boot a device into Fastboot mode:\n\n- Use the `adb` command: From the command-line, type `adb reboot bootloader`.\n- Use a key combination:\n 1. Determine the key combination for your device. For a table of Fastboot key combinations, see [Fastboot key combinations](/docs/setup/reference/fastboot-keys).\n 2. Turn the device off.\n 3. Turn the device on and immediately hold down the key combination for your device (determined in step 1).\n\nUnlock the bootloader\n---------------------\n\nAfter booting into fastboot mode, you must unlock the bootloader.\n| **Warning:** For privacy reasons, unlocking the bootloader deletes user data. After unlocking, all data on the device is erased, including both private app data and shared data accessible over USB (including photos and movies).\n\nTo unlock the bootloader:\n\n1. (Optional) Back up any important files on the device.\n2. Run the unlock command for your device:\n\n - If you're updating a Nexus or Pixel device that is manufactured in 2015 or later, run `fastboot flashing unlock`.\n - For Pixel 2: To flash the bootloader, verify that the Pixel 2's bootloader is updated to at least Oreo MR1's version. To update to a Pixel 2 to this version, apply the over-the-air (OTA) update or sideload a [full OTA](https://developers.google.com/android/ota).\n - For Pixel 2 XL only with loader version prior to TMZ20a: The critical partitions might need to be unlocked before flashing. To unlock the critical partitions on Pixel 2 XL only, run `fastboot flashing unlock_critical`.\n - If you're unlocking a pre-2015 device, run `fastboot oem unlock`.\n\n The target device displays a confirmation screen.\n3. Confirm that you want to erase all user data and unlock the device.\n\n | **Tip:** If your device is shown in the output before reboot, but Fastboot or the flash script are misbehaving, it might be an issue with your USB cable. Try a different port or switching connectors. For example, if you're using a USB C port on your workstation try a USB A port instead.\n\n| **Note:** On Nexus 10, after unlocking the bootloader, the internal storage remains unformatted. You can format the device using `fastboot format cache` followed by `fastboot format userdata`.\n\nFlash a device\n--------------\n\nYou can flash an entire Android system in a single command. Flashing an entire\nsystem with a single command verifies that the system being flashed is\ncompatible with the installed bootloader and radio, writes the boot, recovery,\nand system partitions together, and reboots the system.\n\nTo flash a device:\n\n1. Place the device in fastboot mode by holding the appropriate\n key combination at boot or using the following command:\n\n adb reboot bootloader\n\n2. After the device is in fastboot mode, run:\n\n fastboot flashall -w\n\nThe `-w` option wipes the `/data` partition on the device, which is useful\nfor your first time flashing a particular device.\n| **Note:** File systems created with `fastboot` on Motorola Xoom don't function optimally. Google recommends that you recreate file systems through recovery using `adb reboot recovery`. While in recovery, open the menu (press **Power + Volume Up**), wipe the cache partition, then wipe the data.\n\n### Re-locking the bootloader\n\nTo re-lock the bootloader:\n\n- For 2015 or later devices, run the command `fastboot flashing lock`\n- For 2014 or earlier devices, run the command `fastboot oem lock`\n\nRestore device to factory state\n-------------------------------\n\nFactory images for Google devices are available from\n[Factory Images for Nexus and Pixel Devices](https://developers.google.com/android/nexus/images).\nFactory images for the Motorola Xoom are distributed directly by Motorola."]]
