"Incompatible types" when accessing Map#entrySet()

Here's a demonstration of what you may be doing - it is difficult to be sure without more code.

class ATest<T> {
  Map<String, String> props = new HashMap<String, String>();

  void aTest() {
    // Works fine.
    for (Map.Entry<String, String> entry : props.entrySet()) {
    }
  }

  void bTest() {
    ATest aTest = new ATest();
    // ERROR! incompatible types: Object cannot be converted to Entry<String,String>
    for (Map.Entry<String, String> entry : aTest.props.entrySet()) {
    }
  }

  void cTest(Map props) {
    // ERROR! incompatible types: Object cannot be converted to Entry<String,String>
    for (Map.Entry<String, String> entry : props.entrySet()) {
    }
  }

}

Notice that in bTest I create an ATest without its generic type parameter. In that situation Java removes all generic information from the class, including, as you will see, the <String,String> from the props variable inside it.

Alternatively - you may be accidentally removing the generic nature of the properties map - like I demonstrate in cTest.