Flutter – NoSuchMethod: the method was called on null

This error occurs when attempting to call a method on a null object reference. No such method exists because the call target is null or unassigned. For instance:

foo.bar()Code language: Dart (dart)

will fail with a NoSuchMethod error whenever foo is null. The error will say: NoSuchMethod: the method 'bar' was called on null.

This is the equivalent of a NullReferenceException in C#.

How do I fix it?

Use the call stack to determine the line on which the error occured. Since the name of the method is in the error message, this is usually enough. If not, set a breakpoint on that line and when you reach it, inspect the variable values looking for a null. When you find it, try to understand what led to this state and address it.