spring-projects/spring-framework · error · InvalidPropertyException

Field is not accessible

Error message

Field is not accessible

What it means

InvalidPropertyException thrown by DirectFieldAccessor.DirectFieldAccessorHandler.getValue() when java.lang.reflect.Field.get fails with IllegalAccessException or InaccessibleObjectException even after ReflectionUtils.makeAccessible. This is field-based (not accessor-based) access being blocked by the JVM, typically a module/permission boundary.

Source

Thrown at spring-beans/src/main/java/org/springframework/beans/DirectFieldAccessor.java:147

		@Override
		public TypeDescriptor getCollectionType(int nestingLevel) {
			return new TypeDescriptor(this.resolvableType.getNested(nestingLevel).asCollection().getGeneric(),
					null, this.field.getAnnotations());
		}

		@Override
		public @Nullable TypeDescriptor nested(int level) {
			return TypeDescriptor.nested(this.field, level);
		}

		@Override
		public @Nullable Object getValue() throws Exception {
			try {
				ReflectionUtils.makeAccessible(this.field);
				return this.field.get(getWrappedInstance());
			}
			catch (IllegalAccessException | InaccessibleObjectException ex) {
				throw new InvalidPropertyException(getWrappedClass(),
						this.field.getName(), "Field is not accessible", ex);
			}
		}

		@Override
		public void setValue(@Nullable Object value) throws Exception {
			try {
				ReflectionUtils.makeAccessible(this.field);
				this.field.set(getWrappedInstance(), value);
			}
			catch (IllegalAccessException | InaccessibleObjectException ex) {
				throw new InvalidPropertyException(getWrappedClass(), this.field.getName(),
						"Field is not accessible", ex);
			}
		}
	}

}

View on GitHub (pinned to e8729d0438)

Solutions

1. Add '--add-opens <module>/<package>=ALL-UNNAMED' (or the specific Spring module) to the JVM args.
2. Avoid field access into JDK/JVM internal classes; switch to accessor-based BeanWrapper where possible.
3. If on the classpath as a JPMS module, add 'opens' directives to module-info for the packages Spring must touch.
4. Run on Java 8-15 if you cannot add opens and field access is mandatory (not recommended long-term).

Example fix

# before
java -jar app.jar  # InaccessibleObjectException on field read

# after
java --add-opens java.base/java.lang=ALL-UNNAMED \
     --add-opens my.module/com.example.beans=ALL-UNNAMED \
     -jar app.jar

// Pre-flight field read accessibility under the current JVM
Field f = target.getClass().getDeclaredField(fieldName);
try {
    ReflectionUtils.makeAccessible(f);
    f.setAccessible(true);
    // try a no-op get to confirm
    f.get(target);
} catch (IllegalAccessException | InaccessibleObjectException e) {
    throw new IllegalStateException("Field " + fieldName + " not accessible; add --add-opens", e);
}

static boolean isFieldReadable(Class<?> clazz, String fieldName) {
    try {
        Field f = clazz.getDeclaredField(fieldName);
        f.setAccessible(true);
        f.get(null); // works for static; for instance use a probe instance
        return true;
    } catch (Exception e) { return false; }
}

try {
    return accessor.getPropertyValue(name);
} catch (InvalidPropertyException ex) {
    if ("Field is not accessible".equals(ex.getMessage())) {
        log.error("Add --add-opens {}/{}=ALL-UNNAMED to JVM args",
            fieldDeclaringModule(targetClass), fieldDeclaringPackage(targetClass));
    }
    throw ex;
}

When it happens

Trigger: Using DirectFieldAccessor to read a field on an instance of a class in a non-opened module under JPMS, or running under a SecurityManager that vetoes reflection; field belongs to a JDK class or a third-party module that does not 'open' its package to Spring.

Common situations: Injecting into JDK classes (java.lang, java.util) via field access; Spring test support reflecting into JDK types under Java 16+; SpringBoot on Java 17+ without the recommended --add-opens flags; third-party lib compiled as a JPMS module that doesn't open its packages.

Related errors

• Could not access aspect constructor: {}
• Could not access method [{method}]
• Illegal arguments for constructor
• Could not copy property '${targetPd.getName()}' from source
• Failed to find Java constructor for Kotlin primary construct

AI-assisted analysis of spring-projects/spring-framework@e8729d0438 (2026-08-04). Data as JSON: /data/errors/6581e11e09982ad1.json. Report an issue: GitHub.