spring-projects/spring-framework · error · FatalBeanException

Failed to re-introspect class

Error message

Failed to re-introspect class [{beanClass.getName()}]

What it means

Thrown as FatalBeanException wrapping a java.beans.IntrospectionException when CachedIntrospectionResults.buildGenericTypeAwarePropertyDescriptor cannot construct a GenericTypeAwarePropertyDescriptor for an existing PropertyDescriptor (during interface introspection or re-wrapping). It indicates that re-introspecting an individual property descriptor failed even though the initial BeanInfo was obtained.

Solutions

1. Look at the wrapped IntrospectionException cause to find the offending property and its methods.
2. Make the implementing class's accessors signature-compatible with the interface accessors.
3. Remove or correct the offending interface accessor (e.g. a setter whose parameter type does not match the getter return type).
4. Avoid exposing the problematic property through the interface.

Example fix

// before
interface IFoo { Number getValue(); void setValue(Integer v); }
class Foo implements IFoo { /* value() type clash */ }
new BeanWrapperImpl(new Foo());

// after - consistent types
interface IFoo { Integer getValue(); void setValue(Integer v); }

static boolean interfaceAccessorsConsistent(Class<?> impl, Class<?> ifc) {
    try {
        for (PropertyDescriptor pd : java.beans.Introspector.getBeanInfo(ifc).getPropertyDescriptors()) {
            if (pd.getReadMethod() != null) impl.getMethod(pd.getReadMethod().getName());
        }
        return true;
    } catch (Exception e) { return false; }
}

try {
    new BeanWrapperImpl(bean);
} catch (FatalBeanException ex) {
    // cause is IntrospectionException - fix interface accessor mismatch
    log.error("re-introspection failed for {}", bean.getClass(), ex.getCause());
}

When it happens

Trigger: Inside introspectInterfaces (and similar buildGenericTypeAwarePropertyDescriptor callers), for each interface PropertyDescriptor Spring rebuilds it as GenericTypeAwarePropertyDescriptor; if the read/write methods cannot be reconciled for the target beanClass, the constructor throws IntrospectionException and Spring wraps it.

Common situations: A class implements an interface whose default-method getter/setter has a type incompatible with the implementation, an interface exposing an indexed accessor that doesn't match, or generics erasure causing the descriptor builder to fail to find a consistent property type.

Related errors

• Failed to obtain BeanInfo for class
• Bad indexed read method arg count
• Bad indexed write method arg count
• Bad read method arg count
• Bad write method arg count

AI-assisted analysis of spring-projects/spring-framework@69bf83ad71 (2026-08-09). Data as JSON: /api/errors/3f2bef6fde728231. Report an issue: GitHub.

Appendix: source

Thrown at spring-beans/src/main/java/org/springframework/beans/CachedIntrospectionResults.java:400

			pd = this.propertyDescriptors.get(StringUtils.uncapitalize(name));
			if (pd == null) {
				pd = this.propertyDescriptors.get(StringUtils.capitalize(name));
			}
		}
		return pd;
	}

	PropertyDescriptor[] getPropertyDescriptors() {
		return this.propertyDescriptors.values().toArray(PropertyDescriptorUtils.EMPTY_PROPERTY_DESCRIPTOR_ARRAY);
	}

	private PropertyDescriptor buildGenericTypeAwarePropertyDescriptor(Class<?> beanClass, PropertyDescriptor pd) {
		try {
			return new GenericTypeAwarePropertyDescriptor(beanClass, pd.getName(), pd.getReadMethod(),
					pd.getWriteMethod(), pd.getPropertyEditorClass());
		}
		catch (IntrospectionException ex) {
			throw new FatalBeanException("Failed to re-introspect class [" + beanClass.getName() + "]", ex);
		}
	}

}

View on GitHub (pinned to 69bf83ad71)