MI 9T Pro 4G.K20 Pro Network Fix File ENG QCN File

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

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

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

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• 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

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

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

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Open phone dialer and enter:


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


Connect phone to computer via USB cable



Launch "QPST Configuration" application on Windows



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



Open "QCN Backup Restore Tool" from Start menu



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

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Enter in dialer:


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


Connect phone to PC via USB



Launch "QCN Backup Restore Tool"



Choose the correct COM port from QPST Configuration



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



Restart your phone after successful restore

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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

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[You can add screenshots or video link here]

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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)

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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.

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

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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

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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!

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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!

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