Unhandled exception: type ‘_map‘ is not a subtype of type ‘string’

An unhandled exception with the message “type ‘_map‘ is not a subtype of type ‘string'” typically occurs when you try to assign a variable of type ‘_map’ to a variable of type ‘string’ in your code.

To better understand this error, let’s consider an example:

    
      Map myMap = {
        'key': 'value',
      };
      String myString = myMap; // This line will cause the error
    
  

In the above example, we have declared a variable named ‘myMap’ of type ‘_map‘, and we assign a map with a single key-value pair to it. Then, we attempt to assign the ‘myMap’ to a variable named ‘myString’ of type ‘string’. However, this assignment causes the error because ‘myMap’ is not a string, but a map.

To fix this error, you need to ensure that you are assigning the correct types to your variables. In this case, you should assign the value from the map to the string variable using the key:

    
      Map myMap = {
        'key': 'value',
      };
      String myString = myMap['key']; // This is the correct assignment
    
  

In the updated example, we access the value ‘value’ from the ‘myMap’ using the key ‘key’ and assign it to the ‘myString’ variable. Now, the assignment will work without any errors.