apple/pkl · error · VmException

objectCannotHaveEntry

objectCannotHaveEntry

Error message

Object of type `{0}` cannot have an entry.

What it means

Pkl throws `objectCannotHaveEntry` when an entry (`[key] = value`) appears in an object that cannot hold entries. In elementsEntriesFallback, a typed object class parent, or a Mapping when the literal is elements-only (no entries found and isElementsOnly), triggers this error instead of the element variant.

Solutions

1. Remove the entry from the typed object literal.
2. Convert the entry to a named property (`key = value`) if the class declares it.
3. Change the parent type to Mapping/Dynamic if key-value members are required.

Example fix

// before
new Server { // typed class
  ["port"] = 8080 // entry not allowed
}
// after
new Server {
  port = 8080
}

// Pkl
if (value is TypedObject) {
  throw "entries are not allowed on typed objects; use properties"
}

When it happens

Trigger: Writing `["key"] = value` inside a literal whose parent is a typed object class, or a literal detected as elements-only where entries are disallowed by the parent type.

Common situations: Adding key/value entries to an object declared with a class type; migrating a Dynamic to a typed class without converting entries to properties.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• objectCannotHaveElement
• cannotFindPropertyInObject
• cannotRenderObjectWithElementsAndOtherMembers
• abstractMemberCannotHaveBody
• abstractMethodInNonAbstractType

AI-assisted analysis of apple/pkl@f3efcbfc9b (2026-09-08). Data as JSON: /api/errors/b4eb8bd0e79adaee. Report an issue: GitHub.

Appendix: source

Thrown at pkl-core/src/main/java/org/pkl/core/ast/expression/literal/SpecializedObjectLiteralNode.java:307

    var parentIsClass = parent instanceof VmClass;
    var parentClass = parentIsClass ? (VmClass) parent : VmUtils.getClass(parent);
    VmUtils.checkIsInstantiable(parentClass, getParentNode());

    var property = findFirstNonDefaultProperty(members);
    if (property != null
        && (parentClass == BaseModule.getListingClass()
            || parentClass == BaseModule.getMappingClass())) {
      throw exceptionBuilder()
          .evalError("objectCannotHaveProperty", parentClass)
          .withSourceSection(property.getHeaderSection())
          .build();
    }

    assert firstElemOrEntry != null;

    if (isTypedObjectClass(parentClass)
        || (isElementsOnly && parentClass == BaseModule.getMappingClass())) {
      throw exceptionBuilder()
          .evalError(
              isElementsOnly ? "objectCannotHaveElement" : "objectCannotHaveEntry", parentClass)
          .withSourceSection(firstElemOrEntry.getHeaderSection())
          .build();
    }

    throw exceptionBuilder().unreachableCode().build();
  }
}

View on GitHub (pinned to f3efcbfc9b)