Functions - Terminating a running orchestrator throws IllegalStateException

When using this repo with Azure Functions with the MSSQL backend, and using the client.terminate() API to terminate an orchestraton that is still running, the orchestration will throw an IllegalStateException:

[2025-08-22T16:32:56.240Z] Executed 'Functions.LongRunningOrchestrator' (Failed, Id=c6d1d1b9-32ee-4849-a841-5902bbbff2c6, Duration=51ms)
[2025-08-22T16:32:56.241Z] System.Private.CoreLib: Exception while executing function: Functions.LongRunningOrchestrator. System.Private.CoreLib: Result: Failure
Exception: IllegalStateException: The orchestrator has already completed
Stack: java.lang.IllegalStateException: The orchestrator has already completed
[2025-08-22T16:32:56.242Z]      at com.microsoft.durabletask.Helpers.throwIfOrchestratorComplete(Helpers.java:31)
[2025-08-22T16:32:56.243Z]      at com.microsoft.durabletask.TaskOrchestrationExecutor$ContextImplTask.completeInternal(TaskOrchestrationExecutor.java:799)
[2025-08-22T16:32:56.244Z]      at com.microsoft.durabletask.TaskOrchestrationExecutor$ContextImplTask.fail(TaskOrchestrationExecutor.java:787)
[2025-08-22T16:32:56.244Z]      at com.microsoft.durabletask.TaskOrchestrationExecutor.execute(TaskOrchestrationExecutor.java:71)
[2025-08-22T16:32:56.245Z]      at com.microsoft.durabletask.OrchestrationRunner.loadAndRun(OrchestrationRunner.java:136)
[2025-08-22T16:32:56.247Z]      at com.microsoft.durabletask.OrchestrationRunner.loadAndRun(OrchestrationRunner.java:69)
[2025-08-22T16:32:56.249Z]      at com.microsoft.durabletask.OrchestrationRunner.loadAndRun(OrchestrationRunner.java:42)
[2025-08-22T16:32:56.249Z]      at com.microsoft.durabletask.azurefunctions.internal.middleware.OrchestrationMiddleware.invoke(OrchestrationMiddleware.java:37)
[2025-08-22T16:32:56.250Z]      at com.microsoft.azure.functions.worker.chain.InvocationChain.doNext(InvocationChain.java:21)
[2025-08-22T16:32:56.251Z]      at com.microsoft.azure.functions.worker.broker.JavaFunctionBroker.invokeMethod(JavaFunctionBroker.java:125)
[2025-08-22T16:32:56.252Z]      at com.microsoft.azure.functions.worker.handler.InvocationRequestHandler.execute(InvocationRequestHandler.java:34)
[2025-08-22T16:32:56.253Z]      at com.microsoft.azure.functions.worker.handler.InvocationRequestHandler.execute(InvocationRequestHandler.java:10)
[2025-08-22T16:32:56.254Z]      at com.microsoft.azure.functions.worker.handler.MessageHandler.handle(MessageHandler.java:44)
[2025-08-22T16:32:56.255Z]      at com.microsoft.azure.functions.worker.JavaWorkerClient$StreamingMessagePeer.lambda$onNext$0(JavaWorkerClient.java:94)
[2025-08-22T16:32:56.256Z]      at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
[2025-08-22T16:32:56.257Z]      at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[2025-08-22T16:32:56.258Z]      at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
[2025-08-22T16:32:56.258Z]      at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
[2025-08-22T16:32:56.259Z]      at java.base/java.lang.Thread.run(Thread.java:842)
[2025-08-22T16:32:56.260Z] .
[2025-08-22T16:32:56.266Z] d88614d4-5cea-453a-9bbd-0a423a9059da: Function 'LongRunningOrchestrator (Orchestrator)' failed with an error. Reason: Microsoft.Azure.WebJobs.Host.FunctionInvocationException

Code:

/**
 * Orchestration and activity functions for simulating long-running orchestration and termination.
 */
public class TerminateOrchestration {

    /**
     * This is the orchestrator function.
     */
    @FunctionName("LongRunningOrchestrator")
    public List<String> longRunningOrchestrator(
            @DurableOrchestrationTrigger(name = "ctx") TaskOrchestrationContext ctx,
            final ExecutionContext context) {
        Logger logger = context.getLogger();
        logger.info("Starting long-running orchestration.");
        List<String> outputs = new ArrayList<>();

        // Call our fake activity 100,000 times to simulate an orchestration that might run for >= 10,000s (2.7 hours)
        for (int i = 0; i < 100000; i++) {
            outputs.add(ctx.callActivity("SimulatedWorkActivity", 100, String.class).await());
        }

        return outputs;
    }

    /**
     * This is the activity function.
     */
    @FunctionName("SimulatedWorkActivity")
    public String simulatedWorkActivity(
            @DurableActivityTrigger(name = "sleepMs") int sleepMs,
            final ExecutionContext context) {
        context.getLogger().info("Sleeping for " + sleepMs + "ms.");
        try {
            Thread.sleep(sleepMs);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            return "Sleep interrupted.";
        }
        return "Slept for " + sleepMs + "ms.";
    }

    /**
     * HTTP-triggered function to terminate an orchestration instance.
     */
    @FunctionName("TerminateInstance")
    public HttpResponseMessage run(
            @HttpTrigger(name = "req", methods = {HttpMethod.GET, HttpMethod.POST}, authLevel = AuthorizationLevel.ANONYMOUS) HttpRequestMessage<Optional<String>> request,
            @DurableClientInput(name = "durableContext") DurableClientContext durableContext,
            @BindingName("instanceId") String instanceId,
            final ExecutionContext context) {
        DurableTaskClient client = durableContext.getClient();
        String reason = "Long-running orchestration was terminated early.";
        try {
            client.terminate(instanceId, reason);
            return request.createResponseBuilder(HttpStatus.OK).build();
        } catch (Exception ex) {
            context.getLogger().severe(ex.getMessage());
            return request.createResponseBuilder(HttpStatus.BAD_REQUEST)
                    .header("Content-Type", "text/plain")
                    .body(ex.getMessage())
                    .build();
        }
    }
}

Start by tracing the termination path from DurableTaskClient.terminate(instanceId, reason) into TaskOrchestrationExecutor.execute, especially ContextImplTask.fail and Helpers.throwIfOrchestratorComplete, as shown in the stack trace. Reproduce the issue with the provided TerminateOrchestration functions and verify that terminating a running orchestration no longer causes the IllegalStateException.