Duplicate global key detected in widget tree - flutter

Question

I am facing a problem duplicate global key detected in widget tree when I use static keyword with global key.
If I don't use this static keyword then keyboard hides automatically after few seconds. What should I do?
This is the code that I have tried
`import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:email_validator/email_validator.dart';
import 'package:semesterproject/forgetpassword.dart';
import 'package:semesterproject/home.dart';
import 'package:semesterproject/signup.dart';
import 'package:semesterproject/textfielddec.dart';
class login extends StatelessWidget {
const login({super.key});
#override
Widget build(BuildContext context) {
return Container(
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
colors: [
Colors.purpleAccent,
Colors.lightBlue,
Colors.indigoAccent
]),
),
child: Scaffold(
backgroundColor: Colors.transparent,
body: Center(
child: Container(
height: MediaQuery.of(context).size.height * 0.7,
width: MediaQuery.of(context).size.width * 0.8,
child: CustomForm(),
))),
);
}
}
class CustomForm extends StatefulWidget {
const CustomForm({super.key});
#override
State<CustomForm> createState() => _CustomFormState();
}
class _CustomFormState extends State<CustomForm> {
static final _formkey = GlobalKey<FormState>();
final TextEditingController passcontroller = TextEditingController();
final TextEditingController emailcontroller = TextEditingController();
bool passvisibility = true;
FirebaseAuth _auth = FirebaseAuth.instance;
var errormessage1 = null, errormessage2 = null;
void setpassvisibility() {
setState(() {
passvisibility = !passvisibility;
});
}
Future<void> login() async {
if (_formkey.currentState!.validate()) {
_formkey.currentState!.save();
try {
await _auth
.signInWithEmailAndPassword(
email: emailcontroller.text, password: passcontroller.text)
.then((value) => Navigator.push(
context,
MaterialPageRoute(
builder: (context) => Homepage(),
)));
} on FirebaseAuthException catch (error) {
if (error.code == 'wrong-password') {
setState(() {
errormessage1 = "Incorrect Password!";
});
} else {
setState(() {
errormessage1 = null;
});
}
if (error.code == 'user-not-found') {
setState(() {
errormessage2 = "User email not found";
});
} else {
setState(() {
errormessage2 = null;
});
}
}
}
}
#override
Widget build(BuildContext context) {
return Form(
key: _formkey,
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
Text(
"Login to your Account",
style: TextStyle(
fontSize: 31,
fontWeight: FontWeight.bold,
color: Colors.cyanAccent),
),
SizedBox(
width: MediaQuery.of(context).size.width,
child: TextFormField(
controller: emailcontroller,
style: TextStyle(fontSize: 22),
decoration: InputDecoration(
errorText: errormessage2,
focusedBorder: getfocusedborder(),
enabledBorder: getenabledborder(),
errorBorder: geterrorborder(),
focusedErrorBorder: geterrorfocusedborder(),
hintText: "Email",
hintStyle: TextStyle(fontSize: 22),
errorStyle: TextStyle(fontSize: 18),
),
validator: (value) {
if (value!.isEmpty) return "this field is required";
if (EmailValidator.validate(value) == false)
return "Please enter a valid email";
return null;
},
),
),
SizedBox(
width: MediaQuery.of(context).size.width,
child: TextFormField(
style: TextStyle(fontSize: 22),
controller: passcontroller,
obscureText: passvisibility,
decoration: InputDecoration(
errorText: errormessage1,
focusedBorder: getfocusedborder(),
enabledBorder: getenabledborder(),
errorBorder: geterrorborder(),
focusedErrorBorder: geterrorfocusedborder(),
hintText: "Password",
hintStyle: TextStyle(fontSize: 22),
errorStyle: TextStyle(fontSize: 18),
suffixIcon: IconButton(
onPressed: setpassvisibility,
icon: passvisibility
? Icon(
Icons.visibility_off,
color: Colors.black,
)
: Icon(Icons.visibility),
color: Colors.black,
)),
validator: (value) {
if (value!.isEmpty) return "this field is required";
return null;
},
),
),
InkWell(
child: Text("Forgot password?",
style: TextStyle(color: Colors.amberAccent, fontSize: 22)),
onTap: () => Navigator.push(
context,
MaterialPageRoute(
builder: (context) => forgetpass(),
)),
),
SizedBox(
width: 280,
height: 50,
child: ElevatedButton(
onPressed: () => login(),
child: Text(
"Login",
style: TextStyle(fontSize: 22),
),
style: ElevatedButton.styleFrom(backgroundColor: Colors.indigo),
),
),
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text(
"Don't have an account?",
style: TextStyle(fontSize: 22, color: Colors.amberAccent),
textAlign: TextAlign.center,
),
InkWell(
child: Text("Signup",
style: TextStyle(color: Colors.amber, fontSize: 20)),
onTap: () => Navigator.push(
context,
MaterialPageRoute(
builder: (context) => Signup(),
)),
)
],
),
],
),
);
}
}`
I have go through with different posts of this error but I can't get the solution