apple/pkl · error · VmException

cannotFindPropertyInObjectNoHint

cannotFindPropertyInObjectNoHint

Error message

Cannot find property `{0}` in object of type `{1}`.

What it means

This error is raised when an explicit-receiver property read (`obj.prop`) is evaluated against a `VmReference` (a deferred/reference value in the Pkl runtime) and the referenced object does not expose a property with that name. `evalReference` calls `receiver.withPropertyAccess(propertyName)`, which throws a `VmReferenceAccessError` on a failed member lookup; Pkl converts it into a 'cannot find property' error and attaches a hint describing why the lookup failed (member not found, external member, default member, or external class).

Source

Thrown at pkl-core/src/main/java/org/pkl/core/ast/expression/member/ReadPropertyNode.java:94

          ErrorMessages.create("cannotReferenceExternalProperty", propertyName, err.getType());
      case DEFAULT_MEMBER ->
          ErrorMessages.create(
              "cannotReferenceDefaultProperty",
              ((PType.Class) err.getType()).getPClass().getSimpleName());
      case EXTERNAL_CLASS ->
          ErrorMessages.create(
              "cannotReferencePropertyInExternalClass", propertyName, err.getType());
    };
  }

  @Specialization
  protected VmReference evalReference(VmReference receiver) {
    assert lookupMode == MemberLookupMode.EXPLICIT_RECEIVER;
    try {
      return receiver.withPropertyAccess(propertyName);
    } catch (VmReferenceAccessError err) {
      CompilerDirectives.transferToInterpreter();
      throw exceptionBuilder()
          .evalError("cannotFindPropertyInObjectNoHint", propertyName, receiver.exportType())
          .withHint(getReferenceErrorHint(receiver, err))
          .build();
    }
  }

  // This method effectively covers `VmObject receiver` but is implemented in a more
  // efficient way. See:
  // https://www.graalvm.org/22.0/graalvm-as-a-platform/language-implementation-framework/TruffleLibraries/#strategy-2-java-interfaces
  @Specialization(guards = "receiver.getClass() == cachedClass", limit = "99")
  protected Object evalObject(
      Object receiver,
      @Cached("getVmObjectSubclassOrNull(receiver)") Class<? extends VmObjectLike> cachedClass,
      @Cached("create()") IndirectCallNode callNode) {

    var object = cachedClass.cast(receiver);
    checkConst(object);
    var result = VmUtils.readMemberOrNull(object, propertyName, true, callNode);

View on GitHub (pinned to f3efcbfc9b)

Solutions

1. Read the error hint to see whether the property is missing, external, or default, then fix the property name on the reference read.
2. Verify the property exists on the referent's exported type (check the module/class definition you are referencing).
3. If the property is genuinely optional, guard with `'prop' in obj` or use `obj.getPropertyOrNull("prop")` style access instead of direct dot access.
4. If a dependency module changed, update the consumer code or pin the dependency version.

Example fix

// before
import "myLib.pkl"
output { text = myLib.connctionUrl } // error: no property `connctionUrl`

// after
import "myLib.pkl"
output { text = myLib.connectionUrl }

// Pkl: verify a property exists on the referenced object before reading it
function safeRead(obj: Object, key: String): any? =
  if (key in obj) obj[key] else null

// Pkl: narrow before direct dot access
function hasProp(obj: Object, key: String): Boolean = key in obj
// only use obj.myProp when hasProp(obj, "myProp") is true

// Pkl CLI/eval hosts: wrap module evaluation and inspect VmException for cannotFindProperty errors
try {
  evaluate(module)
} catch (e: PklException) {
  if (e.message.contains("Cannot find property")) {
    // fall back to defaults or report the missing key
  }
}

When it happens

Trigger: Occurs when reading a property through an explicit receiver on a reference-typed value where the property does not exist on the referent's type: e.g. `someModuleRef.typoProp`, accessing a property declared in a sibling type, or referencing an external/default property that cannot be resolved through the reference.

Common situations: Typo'd property names on typed module or object references; a provider module renamed or removed a property so downstream `import` consumers break; accessing a property that exists on the concrete type but not on the declared reference type; reading properties of `external` or default-valued members that the reference cannot access.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• cannotFindPropertyInObject
• cannotFindMember
• defaultMember
• externalMember
• cannotFindPropertyInObject

AI-assisted analysis of apple/pkl@f3efcbfc9b (2026-09-08). Data as JSON: /api/errors/6f66e3908656739c. Report an issue: GitHub.