undefined_named_parameter

The named parameter '{0}' isn't defined.

The analyzer produces this diagnostic when a method or function invocation has a named argument, but the method or function being invoked doesn't define a parameter with the same name.

The following code produces this diagnostic because m doesn't declare a named parameter named a:

class C {
  m({int? b}) {}
}

void f(C c) {
  c.m(a: 1);
}

If the argument name is mistyped, then replace it with the correct name. The example above can be fixed by changing a to b:

class C {
  m({int? b}) {}
}

void f(C c) {
  c.m(b: 1);
}

If a subclass adds a parameter with the name in question, then cast the receiver to the subclass:

class C {
  m({int? b}) {}
}

class D extends C {
  m({int? a, int? b}) {}
}

void f(C c) {
  (c as D).m(a: 1);
}

If the parameter should be added to the function, then add it:

class C {
  m({int? a, int? b}) {}
}

void f(C c) {
  c.m(a: 1);
}

Unless stated otherwise, the documentation on this site reflects Dart 3.8.0. Page last updated on 2025-05-08. View source or report an issue.