Flutter – Text Field and Drop Down should have same height in row

You can use the MediaQuery to adapt your height to all devices, example:

MediaQuery.of(context).size.height * 0.3

But i had used your code to replicate the error and didnt it happening, you can pass all your code to me and i will try replicate the error again, or watch the IntrinsicHeight parent if it have, or some other widget can affect your height and crash your programm, below is the code with a print that worked.

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {

  TextEditingController ageController = TextEditingController();
  String ageErrorMessage = 'Invalid age';
  var selectedGender = 'Male';
  List<String> genders = ['Male', 'Female'];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body:IntrinsicHeight(
        child: Row(
          crossAxisAlignment: CrossAxisAlignment.end,
          children: [
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  const Text(
                    "Age",
                  ),
                  SizedBox(
                      height: 12 ),
                  TextFormField(
                    controller: ageController,
                    decoration: InputDecoration(
                      border: const OutlineInputBorder(),
                      hintText: "Age",
                      isDense: true,
                      errorText: ageErrorMessage,
                    ),
                  ),
                ],
              ),
            ),
            const SizedBox(width: 12),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    "Gender",
                    //style: textStyle,
                  ),
                  SizedBox(
                      height: 12 ),
                  DropdownButtonHideUnderline(
                    child: DropdownButtonFormField<String>(
                      isExpanded: true,
                      decoration: const InputDecoration(
                          border: OutlineInputBorder(),
                          contentPadding: EdgeInsets.symmetric(
                              horizontal: 8.0, vertical: 14.5)),
                      hint: Text(
                        'Gender',
                        // style: textStyle,
                      ),
                      value: selectedGender,
                      //validator: validate,
                      borderRadius: BorderRadius.circular(20),
                      items: genders.map((String gender) {
                        return DropdownMenuItem<String>(
                          value: gender,
                          child: Text(
                            gender,
                            style: TextStyle(
                                fontSize: 14.0,
                                fontWeight: FontWeight.w400),
                          ),
                        );
                      }).toList(),
                      onChanged: (String? value) {},
                    ),
                  ),
                ],
              ),
            )
          ],
        ),
      ),
    );
  }
}