Debugging mode on USB Xiaomi Redmi 9: how to turn on in 5 minutes

Why do I need USB debugging mode on Redmi 9?

USB Debugging Mode (USB Debugging) is a hidden Android feature that opens up access to low-level developer tools. On Xiaomi Redmi 9 (models M2003J15SC, M2004C3LGG and others), this mode is required to:

Install custom firmware via fastboot or TWRP;

Unlock the bootloader in the official way;

— Work with ADB-commands (for example, to transfer applications to a memory card);

- Data recovery after a reset or "brick" of the device;

Testing applications through Android Studio.

Without debugging activation, even connecting to a PC via the Mi Flash Tool or Xiaomi ADB/Fastboot Tools will be limited. However, on the Redmi 9 with MIUI 12+, the path to enabling mode is different from standard Android - due to its security policy, Xiaomi hides the default "Developers" item.

This guide provides current ways to enable debugging for all MIUI versions (including global, Chinese and European firmware), as well as solving common errors such as "Unauthorized" or the absence of a device in ADB devices.

Preparation: What you will need before turning on debugging

Before you activate the mode, make sure that:

• 📱 Battery charge at least 50%. When connected to a PC, the device can discharge faster due to active data transfer.
• 🔌 Cable USB — Original or certified (cheap cables often don’t transmit data, only charge).
• 💻 Computer with installed Xiaomi drivers (you can download on the official website).
• 🔓 Unlocked screen. You can't debug on a locked device.

If you plan to use ADB or Fastboot, install:

• 🛠️ Google Platform Tools (includes adb.exe and fastboot.exe).
• 🔧 Mi Unlock Tool (if the goal is to unlock the bootloader).

⚠️ Attention: Redmi 9 with firmware MIUI 13+ When you first connect to a PC, you might get a debugging permission request from that computer, and if you don't confirm it within 10 seconds, the device automatically rejects the connection, and you have to reconnect the cable.

💡

If debugging is needed to unlock the bootloader, pre-link your Mi Account to the device in Settings → Xiaomi Account. Without this, the Mi Unlock Tool will not work.

Step 1: Activate Developer Mode on Redmi 9

By default, the "Developers" item is hidden in MIUI. To open it:

1. Go to Settings. → The phone.
2. Find the line "Version" MIUI" And tap it 7 times in a row.
3. After 3-4 taps, a pop-up notification will appear: “You’re almost there!”.
4. At press 7, the system will say, “You’ve become a developer!”

If the line "Version" MIUI" Inactive (in gray), so it is not:

• 🔒 The device is blocked by corporate policy (for example, if the phone was issued by the employer).
• 📱 Unofficial firmware installed without developer mode support.
• 🔄 Renewable. MIUI Up to the latest version (through Settings) → Updating the system).

⚠️ Note: On some versions MIUI 14 for Redmi 9 after activation of the developer mode, it may be necessary to restart the device so that the item appears in the settings menu.

Stashed on "Version." MIUI" 7 times|You have received a notice saying, “You have become a developer!"|In the menu "Settings" appeared the item "Additional" → For developers"|Reboot the phone (if required)-->

Step 2: Enabling USB debugging in the developer menu

After activating the developer mode:

1. Return to the main settings menu.
2. Go to Additional → For developers (on some firmware, the path may be Settings → System → Additional → For developers).
3. Scroll down to the debugging block.
4. Activate the "Debugging by USB" switch.
5. In the confirmation window that appears, click "OK".

If the USB Debugging switch is inactive (grey and does not click), check:

• 🔌 Is the phone connected to the PC by USB (on some firmware debugging can be enabled only when connected).
• 🔒 Whether “Unblocking” is permitted OEM" In the same menu (need to unlock the loader).
• 📱 Are there any restrictions in the “Data Protection” settings.

Redmi 9 with MIUI 12.5+ may have an additional request for a password/pattern lock to confirm debugging, which is normal because Xiaomi protects the device from unauthorized access.

Step 3: Connect to PC and confirm debugging

After turning on the debugging on the phone:

1. Connect Redmi 9 to your PC via USB-cable.
2. On the phone in the notification bar will be a request: “Allow debugging over USB?”.
3. Check "Always allow from this computer" and click "Allow".

If the request does not appear:

• 🔄 Try reconnecting the cable (sometimes changing the port helps). USB PC-only).
• 📱 Restart your phone and PC.
• 🔧 Install Xiaomi drivers manually through Device Manager (if Windows doesn’t recognize the phone).

To check the success of the connection:

1. Open Command Prompt on PC (Win + R → enter cmd).
2. Go to the folder with the platform-tools (for example, cd C:\platform-tools).
3. Enter the command: Adb devices
4. If the device serial number appears in the answer (for example, 1234abcd device), the debugging works.

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If the adb device command returns a blank list, but the phone charges - the problem is in the drivers or settings USB-connection on the phone (should be selected mode "Sending files").

Solving common errors when enabling debugging

Even after properly activating debugging, Redmi 9 users face typical problems:

1. Unauthorized error in ADB

Reason: The phone didn't confirm trust in the PC or reset the list of authorized devices.

Decision:

• 🔄 Turn it off and plug it back in. USB-cable.
• 📱 On the phone in the notifications should appear a request for debugging permission – confirm it.
• 🗑️ If the request does not appear, delete the adbkeys file in the folder %USERPROFILE%\.Android on PC and restart ADB.

2. the Developer Menu is not available after the update

Reason: Resetting settings or firmware bug.

Decision:

• 🔧 Repeat the "Version" 7 times. MIUI".
• 📱 If it doesn’t help, reset the settings to factory (without deleting data): Settings → The phone. → Resetting settings → Reset the settings.

3.The phone is not identified in Fastboot

Reason: Fastboot drivers are not installed or the bootloader is blocked.

Decision:

• 💻 Install drivers via Mi Flash Tool (download on the official website).
• 🔧 Turn on "Unlock" OEM" developer-menu.
• 🔄 Reboot your phone in Fastboot manually: Turn off the device, then press Volume down + 10 seconds power.

⚠️ Attention: Redmi 9 with firmware MIUI 13.0.4+ When connecting in Fastboot mode, you may need to log in via your Mi Account. If you did not link your account in advance, unlocking the bootloader will not be possible without a reset.

Additional settings for experienced users

If you plan to use debugging for advanced operations (firmware, system modification), pay attention to these parameters in the menu "For developers":

• 🔓 Unlocking OEM — It is required to unlock the bootloader. On some firmware hidden and requires activation through the ADB: adb shell settings put global oem_unlock_enabled 1
• 📶 Turn off the absolute volume level – it is useful if the sound in the headphones is too quiet.
• 🔄 Do not turn off the screen when charging - convenient for long operations with ADB.
• 🛠️ Include the journal HCI Bluetooth – needed to debug problems with Bluetooth devices.

Redmi 9s. MIUI 14 new option appears — "USB-Default configuration" It is recommended to set the value "File transfer" or "PTP", To avoid problems with device recognition in ADB.

FAQ: Frequent questions about debugging on Redmi 9