Mi 3 QCN

What is Xiaomi QCN File? How to Backup & Restore? [Complete Guide]​

What is a QCN File?​

QCN (Qualcomm Calibration Network) file is a backup file that stores critical network calibration data for Xiaomi devices with Qualcomm processors.

What Does It Contain?​

• IMEI number (device identifier)
• Network calibration data
• Baseband configuration
• RF (Radio Frequency) parameters
• NV (Non-Volatile) memory items

---

When and Why Is It Used?​

Problems That Require QCN:​

• Lost IMEI: IMEI shows as null or unknown
• No Network Connection: Cannot connect to mobile networks
• Invalid Baseband: Baseband version shows as unknown
• Post-ROM Issues: Network problems after installing custom ROM

When Should You Backup?​

• Before unlocking bootloader
• Before installing custom ROM
• Before any major system modifications
• When device is working perfectly (preventive backup)

---

Required Tools​

✓ QPST Tools (Qualcomm Product Support Tools)✓ Qualcomm USB Drivers✓ Windows PC✓ USB Cable

---

QCN BACKUP STEP-BY-STEP​

Enable Diag Mode​

Open phone dialer and enter:


*#*#717717#*#*<br>

Connect to PC​

Connect phone to computer via USB cable

Open QPST​

Launch "QPST Configuration" application on Windows

Add Port​

Click "Add New Port" button and select the Diag port

Start QCN Tool​

Open "QCN Backup Restore Tool" from Start menu

Backup​

Select COM port → Click "Backup" button → Save QCN file

---

QCN RESTORE STEP-BY-STEP​

Diag Mode​

Enter in dialer:


*#*#717717#*#*<br>

Connect Device​

Connect phone to PC via USB

Open Tool​

Launch "QCN Backup Restore Tool"

Select Port​

Choose the correct COM port from QPST Configuration

Restore​

Click "Restore" → Browse and select your QCN file → Confirm

Reboot​

Restart your phone after successful restore

---

IMPORTANT WARNINGS​

MUST KNOW:

• Use QCN file ONLY on the SAME device (never share between devices)
• Keep your QCN backup in a safe place
• Wrong QCN file can cause permanent network issues
• Some regions have legal restrictions on IMEI modification

---

Visual Guide​

[You can add screenshots or video link here]

---

Tips & Tricks​

Backup QCN when your device is working properly Store backup file in multiple locations (PC + Cloud) Create new backup before each major operation Add date to QCN filename (e.g., qcn_backup_2024_01_12.qcn)

---

Frequently Asked Questions​

Q: Can I use QCN file on another phone?A: No! Each QCN file is unique to that specific device.


Q: Will I lose QCN when installing custom ROM?A: In some cases yes, that's why you should backup beforehand.


Q: Where can I download QPST tools?A: From official Qualcomm website or XDA forums.


Q: IMEI still shows null after restore?A: Reboot device, try factory reset, or contact Xiaomi service center.


Q: Is this legal?A: Backing up and restoring your own device's QCN is legal. However, changing IMEI or using someone else's QCN may be illegal in some countries.


Q: My device is not detected in QPST?A: Make sure you've installed Qualcomm drivers correctly and enabled Diag mode.

---

Useful Links​

• QPST Tools Download: [add link]
• Video Tutorial: [add link]
• XDA Thread: [add link]
• Qualcomm Drivers: [add link]

---

Troubleshooting​

Problem: Port not showing in QPST

• Solution: Reinstall Qualcomm drivers, try different USB port

Problem: Backup fails

• Solution: Disable antivirus temporarily, run QPST as administrator

Problem: After restore, no network

• Solution: Reboot phone, check airplane mode, verify QCN file

Problem: "Access Denied" error

• Solution: Enable Developer Options, enable USB debugging

---

Compatible Devices​

This method works on Xiaomi devices with Qualcomm chipsets:

• Redmi Note series
• POCO series
• Mi series
• Redmi series (with Snapdragon processors)

Note: Does NOT work on MediaTek chipset devices!

---

Disclaimer: This guide is for educational purposes only. Always backup your data before making modifications. The author is not responsible for any damage to your device.


If this helped you, please hit the thanks button!

---

Feel free to leave comments if you have questions. I'll try to help!


Last Updated: January 2025