invalid_assignment

A value of type '{0}' can't be assigned to a variable of type '{1}'.

The analyzer produces this diagnostic when the static type of an expression that is assigned to a variable isn't assignable to the type of the variable.

The following code produces this diagnostic because the type of the initializer (int) isn't assignable to the type of the variable (String):

int i = 0;
String s = i;

If the value being assigned is always assignable at runtime, even though the static types don't reflect that, then add an explicit cast.

Otherwise, change the value being assigned so that it has the expected type. In the previous example, this might look like:

int i = 0;
String s = i.toString();

If you can't change the value, then change the type of the variable to be compatible with the type of the value being assigned:

int i = 0;
int s = i;

Unless stated otherwise, the documentation on this site reflects Dart 3.7.3. Page last updated on 2025-05-08. View source or report an issue.