apache/beam · error · UnsupportedOperationException

ValueKind unsupported in

Error message

ValueKind unsupported in %s

What it means

DoFnInvoker's UnsupportedInvocationBehavior throws this when a callback calls valueKind() in an invocation context that cannot report whether the current value is a plain element or a bundle-final element. valueKind() is a splittable-DoFn / specialized-runner concept; the default behavior has no kind to report and refuses the call. The message context names the DoFn and callback that made the invalid request.

Solutions

1. Remove the valueKind() call unless you specifically depend on bundle-final element semantics and run on a supporting runner
2. Default the kind when unavailable: catch UnsupportedOperationException and treat it as the ordinary-element kind
3. Test the DoFn with TestPipeline / runner-backed DoFnRunner instead of the default invoker
4. If ValueKind is essential, ensure the execution path uses a DoFnRunner implementation that supports it (e.g. SplittableDoFn paths)

Example fix

// before
ValueKind kind = context.valueKind();
// after
ValueKind kind;
try { kind = context.valueKind(); } catch (UnsupportedOperationException e) { kind = ValueKind.ELEMENT; }

// Only read valueKind() when running on a runner path that supports it;
// in ordinary DoFns treat every element as ValueKind.ELEMENT.

DoFn.ValueKind safeValueKind(DoFn.ProcessContext ctx) {
  try { return ctx.valueKind(); }
  catch (UnsupportedOperationException e) { return DoFn.ValueKind.ELEMENT; }
}

try {
  DoFn.ValueKind kind = context.valueKind();
} catch (UnsupportedOperationException e) {
  DoFn.ValueKind kind = DoFn.ValueKind.ELEMENT; // assume ordinary element
}

When it happens

Trigger: Calling context.valueKind() from @ProcessElement or timer callbacks when the DoFn is invoked with UnsupportedInvocationBehavior — e.g. via DoFnInvokers.invokerFor(...) in tests or on runners without ValueKind support.

Common situations: Writing DoFn code that references valueKind() but running it on a runner or test harness that never sets it; copying splittable-DoFn idioms into ordinary DoFns; custom runner implementations lacking this API.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• RecordId unsupported in
• RecordOffset unsupported in
• Cannot access fire timestamp outside of @OnTimer method.
• Cannot access timerId as parameter outside of @OnTimer…
• CausedByDrain unsupported in

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/1b979078c7d16c44. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/reflect/DoFnInvoker.java:378

      throw new UnsupportedOperationException(
          String.format("FireTimestamp unsupported in %s", getErrorContext()));
    }

    @Override
    public CausedByDrain causedByDrain(DoFn<InputT, OutputT> doFn) {
      throw new UnsupportedOperationException(
          String.format("CausedByDrain unsupported in %s", getErrorContext()));
    }

    @Override
    public ValueKind valueKind(DoFn<InputT, OutputT> doFn) {
      throw new UnsupportedOperationException(
          String.format("ValueKind unsupported in %s", getErrorContext()));
    }

    @Override
    public String timerId(DoFn<InputT, OutputT> doFn) {
      throw new UnsupportedOperationException(
          String.format("TimerId unsupported in %s", getErrorContext()));
    }

    @Override
    public TimeDomain timeDomain(DoFn<InputT, OutputT> doFn) {
      throw new UnsupportedOperationException(
          String.format("TimeDomain unsupported in %s", getErrorContext()));
    }

    @Override
    public OutputReceiver<OutputT> outputReceiver(DoFn<InputT, OutputT> doFn) {
      throw new UnsupportedOperationException(
          String.format("OutputReceiver unsupported in %s", getErrorContext()));
    }

    @Override
    public OutputReceiver<Row> outputRowReceiver(DoFn<InputT, OutputT> doFn) {
      throw new UnsupportedOperationException(

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