undefined_unqualified_name_write

'{0}' is final, so it can't be assigned to.

The constant '{0}' can't be assigned to.

The {0} '{1}' can't be assigned to.

There's a getter '{0}', but no setter.

Undefined name '{0}'.

The analyzer produces this diagnostic when a name without a qualifier is assigned, but there's no setter or variable that can be assigned with that name in the scope in which it's used.

The following code produces this diagnostic because the name cuont isn't defined:

var count = 0;
​
void f() {
  cuont = 1;
}

The following code produces this diagnostic because there's only a getter named x:

int get x => 0;
​
void f() {
  x = 1;
}

The following code produces this diagnostic because y is final:

final y = 0;
​
void f() {
  y = 1;
}

The following code produces this diagnostic because m is a method:

class C {
  void m() {}
​
  void f() {
    m = () {};
  }
}

If the name is misspelled, then correct it:

var count = 0;
​
void f() {
  count = 1;
}

If there's only a getter, then add a setter with the same name:

int get x => 0;
​
set x(int _) {}
​
void f() {
  x = 1;
}

If the variable is final, then make it non-final:

var y = 0;
​
void f() {
  y = 1;
}

Otherwise, remove the assignment, or assign to a variable instead.