This is usually a driver issue. Try a different USB port (USB 2.0 is often more reliable than 3.0 for legacy devices) or a different cable.
Do not use an autoloader if the device is working normally — standard OTA or official desktop updates are safer for routine updates because they preserve more user data. blackberry autoloader firmware file
Once detected, the autoloader will automatically: This is usually a driver issue
A typical Autoloader file (e.g., BlackBerry10.3.3.3216_Q10_Autoloader.exe ) contains several critical components packaged into one: blackberry autoloader firmware file