Use **side** property of OutlinedButton. Don't use it inside the shape property of OutlinedButton.
```
OutlinedButton(
onPressed: () {},
style: OutlinedButton.styleFrom(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(10),
// side: BorderSide(width:1.0, color: Colors.red), // DON'T USE HERE
),
side: BorderSide(width:1.0, color: Colors.red),
minimumSize: Size( width * 0.25, height * 0.04),
),
child: Text('Decline', style: TextStyle(color: Colors.red),),
),
```
You can do it with `side: BorderSide()`
Example:
OutlinedButton.icon(
onPressed: () async {},
icon: Icon(Icons.person_add),
label: Text("Import"),
style: OutlinedButton.styleFrom(
side: BorderSide(width: 2, color: Colors.green),
backgroundColor: Colors.white,
primary: Theme.of(context).primaryColorDark,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.all(
Radius.circular(2),
),
),
),
)
