spring-projects/spring-framework · error · NullValueInNestedPathException

Cannot access indexed value in property referenced in…

Error message

Cannot access indexed value in property referenced in indexed property path '{tokens.canonicalName}': returned null

What it means

Thrown by getPropertyHoldingValue when the holding value for a keyed write is null and setAutoGrowNestedPaths is false. Without auto-grow Spring cannot create the container, so it raises NullValueInNestedPathException naming the canonical path.

Solutions

Initialize the collection/map field: e.g. private List<T> items = new ArrayList<>();.
Call wrapper.setAutoGrowNestedPaths(true) before the write (propagated to nested accessors).
Set the holding property to a non-null container before addressing an index/key.
Pre-flight check getPropertyValue(base) for null and instantiate explicitly.

Example fix

// before
private List<String> items; // null
wrapper.setPropertyValue("items[0]", "a");

// after
private List<String> items = new ArrayList<>();
// or
wrapper.setAutoGrowNestedPaths(true);

Defensive patterns

Strategy: validation

Validate before calling

BeanWrapper w = new BeanWrapperImpl(bean);
String base = path.substring(0, path.indexOf('['));
Object holder = w.getPropertyValue(base);
if (holder == null) {
    // either initialize the field or enable autogrow
    w.setAutoGrowNestedPaths(true);
}
w.setPropertyValue(path, value);

Type guard

static boolean holderNotNull(BeanWrapper w, String path) {
    String base = path.substring(0, path.indexOf('['));
    return w.getPropertyValue(base) != null;
}

Try / catch

try {
    wrapper.setPropertyValue(path, value);
} catch (NullValueInNestedPathException ex) {
    if (ex.getMessage().contains("returned null")) { /* initialize container or enable autogrow */ }
    else throw ex;
}

Prevention

Initialize collection/map fields inline (private List<T> items = new ArrayList<>();).
Enable setAutoGrowNestedPaths(true) when binding onto beans with null containers.
Return empty containers from getters instead of null.

When it happens

Trigger: setProperty("items[0]", value) where getItems() returns null and autoGrowNestedPaths is disabled (the default in some contexts).

Common situations: Bean field left null with no initializer; binding into a freshly constructed bean whose collection/map fields are null; autoGrow turned off for safety; nested wrapper created without inheriting autoGrow settings.

Related errors

AI-assisted analysis of spring-projects/spring-framework@69bf83ad71 (2026-08-09). Data as JSON: /api/errors/84494e4436ee035e. Report an issue: GitHub.

Appendix: source

Thrown at spring-beans/src/main/java/org/springframework/beans/AbstractNestablePropertyAccessor.java:386

		Object propValue;
		try {
			propValue = getPropertyValue(getterTokens);
		}
		catch (NotReadablePropertyException ex) {
			throw new NotWritablePropertyException(getRootClass(), this.nestedPath + tokens.canonicalName,
					"Cannot access indexed value in property referenced " +
					"in indexed property path '" + tokens.canonicalName + "'", ex);
		}

		if (propValue == null) {
			// null map value case
			if (isAutoGrowNestedPaths()) {
				int lastKeyIndex = tokens.canonicalName.lastIndexOf('[');
				getterTokens.canonicalName = tokens.canonicalName.substring(0, lastKeyIndex);
				propValue = setDefaultValue(getterTokens);
			}
			else {
				throw new NullValueInNestedPathException(getRootClass(), this.nestedPath + tokens.canonicalName,
						"Cannot access indexed value in property referenced " +
						"in indexed property path '" + tokens.canonicalName + "': returned null");
			}
		}
		return propValue;
	}

	private void processLocalProperty(PropertyTokenHolder tokens, PropertyValue pv) {
		PropertyHandler ph = getLocalPropertyHandler(tokens.actualName);
		if (ph == null || !ph.isWritable()) {
			if (pv.isOptional()) {
				if (logger.isDebugEnabled()) {
					logger.debug("Ignoring optional value for property '" + tokens.actualName +
							"' - property not found on bean class [" + getRootClass().getName() + "]");
				}
				return;
			}
			if (this.suppressNotWritablePropertyException) {

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