The “No converter found capable of converting from type [org.springframework.data.jpa.repository.query.abstractjpaquery$tupleconverter$tuplebackedmap] to type” error occurs when you are trying to convert between incompatible types in Spring Data JPA.
This error typically happens when you are using projections or custom queries in your JPA repository, and the types involved in the query do not match with the expected result types.
To illustrate this with an example, suppose you have a JPA repository method like this:
public List<CustomProjection> findCustomProjections();
And you have defined a custom projection interface like this:
public interface CustomProjection {
String getName();
}
If you mistakenly declare the return type as List<Map<String, Object>> in the repository method instead of List<CustomProjection>, you will encounter the “No converter found capable of converting from type” error.
To fix this error, ensure that the return type of your repository method matches the expected result types. In the example above, you should change the method signature to:
public List<CustomProjection> findCustomProjections();