Repair NV/EFS using Qualcomm tools (if EFS backup not available)
Settings → System → Reset → Reset Wi-Fi, mobile & Bluetooth. repair imei sony xz3
The IMEI is a unique identifier stored in the device's NVRAM (Non-Volatile Random Access Memory). If this partition becomes corrupted, your phone displays "Invalid IMEI" or "IMEI 0" when you dial Repair NV/EFS using Qualcomm tools (if EFS backup