Flutter - 'initialValue == null || controller == null': is not true. error

I'm trying to set an initial value for the text field. But I Can't set the initial value in text form field. I'm getting this error 'initialValue == null || controller == null': is not true .

code:

 Widget buildFirstName(BuildContext context) {
 valueBuilder = valueBuild();

return TextFormField(
  controller: firstNameController,
  initialValue: valueBuilder,
  decoration: InputDecoration(
    hintText: "Enter Name",
    fillColor: Colors.white,
    hintStyle: TextStyle(
        color: Color.fromRGBO(0, 0, 0, 1.0),
        fontFamily: "SFProText-Regular"),
  ),
  validator: validatingName,
);

}

You can't use both initialValue and controller at the same time. So, it's better to use controller as you can set default text in its constructor.

Here is an example.

// Create the controller. 
final controller = TextEditingController(text: "Your initial value");

Widget build(BuildContext context) {
  return TextFormField(
    controller: controller, // Assign it here. 
    // ...
  );
}

To get the value entered by the user, use:

controller.text