spring-projects/spring-framework · error · BeanInstantiationException

No default constructor found

Error message

No default constructor found

What it means

Thrown as BeanInstantiationException by instantiateClass(Class) when clazz.getDeclaredConstructor() (no-arg) raises NoSuchMethodException and findPrimaryConstructor(clazz) also returns null. This means the class has neither a no-arg constructor nor a resolvable primary/canonical constructor (Kotlin primary or Java record canonical), so Spring cannot pick one (BeanUtils.java:136-145).

Source

Thrown at spring-beans/src/main/java/org/springframework/beans/BeanUtils.java:143

	 * primary/default constructor was found, a {@link NoClassDefFoundError}
	 * or other {@link LinkageError} in case of an unresolvable class definition
	 * (for example, due to a missing dependency at runtime), or an exception thrown
	 * from the constructor invocation itself.
	 * @see Constructor#newInstance
	 */
	public static <T> T instantiateClass(Class<T> clazz) throws BeanInstantiationException {
		Assert.notNull(clazz, "Class must not be null");
		if (clazz.isInterface()) {
			throw new BeanInstantiationException(clazz, "Specified class is an interface");
		}
		Constructor<T> ctor;
		try {
			ctor = clazz.getDeclaredConstructor();
		}
		catch (NoSuchMethodException ex) {
			ctor = findPrimaryConstructor(clazz);
			if (ctor == null) {
				throw new BeanInstantiationException(clazz, "No default constructor found", ex);
			}
		}
		catch (LinkageError err) {
			throw new BeanInstantiationException(clazz, "Unresolvable class definition", err);
		}
		return instantiateClass(ctor);
	}

	/**
	 * Instantiate a class using its no-arg constructor and return the new instance
	 * as the specified assignable type.
	 * <p>Useful in cases where the type of the class to instantiate (clazz) is not
	 * available, but the type desired (assignableTo) is known.
	 * <p>Note that this method tries to set the constructor accessible if given a
	 * non-accessible (that is, non-public) constructor.
	 * @param clazz class to instantiate
	 * @param assignableTo type that clazz must be assignableTo
	 * @return the new instance

View on GitHub (pinned to e8729d0438)

Solutions

1. Add a public no-arg constructor to the class.
2. Resolve the constructor yourself with getDeclaredConstructor(argTypes...) and call instantiateClass(ctor, args).
3. Use getResolvableConstructor to obtain a single unique constructor and supply matching arguments.
4. For Kotlin classes ensure the kotlin-reflect dependency is present so the primary constructor can be found.

Example fix

// before
public class User { public User(String name) {} }
BeanUtils.instantiateClass(User.class); // no default ctor

// after
Constructor<User> c = User.class.getDeclaredConstructor(String.class);
BeanUtils.instantiateClass(c, "Alice");

Constructor<?> def;
try { def = clazz.getDeclaredConstructor(); }
catch (NoSuchMethodException e) { def = null; }
if (def == null && BeanUtils.findPrimaryConstructor(clazz) == null) {
  // resolve an explicit constructor and pass args instead
}

public static boolean hasDefaultOrPrimaryCtor(Class<?> c) {
  try { c.getDeclaredConstructor(); return true; }
  catch (NoSuchMethodException e) { return BeanUtils.findPrimaryConstructor(c) != null; }
}

try { BeanUtils.instantiateClass(clazz); }
catch (BeanInstantiationException e) {
  Constructor<?> c = clazz.getDeclaredConstructor(String.class);
  BeanUtils.instantiateClass(c, arg);
}

When it happens

Trigger: instantiateClass(Foo.class) on a Java class whose only constructors take arguments and that is neither a Kotlin class with a primary constructor nor a record. The NoSuchMethodException is retained as the cause.

Common situations: Refactoring a class to add a required-args constructor and removing the no-arg one; instantiating an immutable/value type by class only; integration code assuming a default constructor exists.

Related errors

• Specified class is an interface
• Is it an abstract class?
• Is the constructor accessible?
• Unresolvable class definition
• Illegal arguments for constructor

AI-assisted analysis of spring-projects/spring-framework@e8729d0438 (2026-08-04). Data as JSON: /data/errors/bcac2ac8d3664bab.json. Report an issue: GitHub.