spring-projects/spring-framework · error · BeanInstantiationException

Constructor threw exception

Error message

Constructor threw exception

What it means

Thrown as BeanInstantiationException by instantiateClass(Constructor, args) when the constructor's own body throws; Constructor.newInstance wraps it in InvocationTargetException and Spring unwraps the original target exception as the cause (BeanUtils.java:219-221). The failure originates in user/library constructor code, not in Spring.

Source

Thrown at spring-beans/src/main/java/org/springframework/beans/BeanUtils.java:220

					}
					else {
						argsWithDefaultValues[i] = args[i];
					}
				}
				return ctor.newInstance(argsWithDefaultValues);
			}
		}
		catch (InstantiationException ex) {
			throw new BeanInstantiationException(ctor, "Is it an abstract class?", ex);
		}
		catch (IllegalAccessException ex) {
			throw new BeanInstantiationException(ctor, "Is the constructor accessible?", ex);
		}
		catch (IllegalArgumentException ex) {
			throw new BeanInstantiationException(ctor, "Illegal arguments for constructor", ex);
		}
		catch (InvocationTargetException ex) {
			throw new BeanInstantiationException(ctor, "Constructor threw exception", ex.getTargetException());
		}
	}

	/**
	 * Return a resolvable constructor for the provided class, either a primary or single
	 * public constructor with arguments, a single non-public constructor with arguments
	 * or simply a default constructor.
	 * <p>Callers have to be prepared to resolve arguments for the returned constructor's
	 * parameters, if any.
	 * @param clazz the class to check
	 * @throws IllegalStateException in case of no unique constructor found at all
	 * @since 5.3
	 * @see #findPrimaryConstructor
	 */
	@SuppressWarnings("unchecked")
	public static <T> Constructor<T> getResolvableConstructor(Class<T> clazz) {
		Constructor<T> ctor = findPrimaryConstructor(clazz);
		if (ctor != null) {

View on GitHub (pinned to e8729d0438)

Solutions

1. Read the cause (and its stack trace) to find the line in the constructor that threw, then fix that code.
2. Ensure collaborators/resources the constructor depends on are available before instantiation.
3. Supply valid constructor arguments that satisfy the constructor's invariants.
4. Move expensive/fallible logic out of the constructor into an @PostConstruct or initializer method.

Example fix

// before
public User(String name) { if (name == null) throw new IllegalArgumentException("name"); }
BeanUtils.instantiateClass(ctor, null); // ctor throws

// after
BeanUtils.instantiateClass(ctor, "Alice");

// Verify preconditions the constructor enforces before calling
// e.g. if (name == null) throw ... -> ensure name != null before instantiate

public static boolean ctorArgsSatisfyInvariants(Constructor<?> c, Object[] args) {
  // project-specific: check non-null/type constraints derived from ctor Javadoc/validation
  return Arrays.stream(args).noneMatch(Objects::isNull) || c.getParameterCount() == 0;
}

try { BeanUtils.instantiateClass(ctor, args); }
catch (BeanInstantiationException e) {
  Throwable real = e.getCause(); // the constructor's own exception; fix its source
}

When it happens

Trigger: instantiateClass(ctor, args) where the constructor executes code that throws (NullPointerException, IllegalStateException, IllegalArgumentException, a domain exception, etc.). The thrown exception is propagated verbatim as the cause.

Common situations: A bean constructor validating arguments and throwing; field initialization that fails (e.g. loading a resource that is missing); constructor calling a collaborator that is null/unconfigured; defensive constructors rejecting bad state.

Related errors

• Specified class is an interface
• Is it an abstract class?
• Is the constructor accessible?
• No default constructor found
• Unresolvable class definition

AI-assisted analysis of spring-projects/spring-framework@e8729d0438 (2026-08-04). Data as JSON: /data/errors/b30b9b8d975a2134.json. Report an issue: GitHub.