diff --git a/crates/sdk-core/src/core_tests/mod.rs b/crates/sdk-core/src/core_tests/mod.rs
index 29f5df27c..cc5169404 100644
--- a/crates/sdk-core/src/core_tests/mod.rs
+++ b/crates/sdk-core/src/core_tests/mod.rs
@@ -14,21 +14,38 @@ use crate::{
     },
     worker::{
         PollerBehavior,
-        client::mocks::{mock_manual_worker_client, mock_worker_client},
+        client::mocks::{
+            DEFAULT_WORKERS_REGISTRY, MockManualWorkerClient, mock_manual_worker_client,
+            mock_worker_client,
+        },
     },
 };
 use futures_util::FutureExt;
-use std::{sync::LazyLock, time::Duration};
+use std::{
+    future,
+    sync::{Arc, LazyLock},
+    time::Duration,
+};
 use temporalio_common::protos::{
     coresdk::{
         workflow_activation::{WorkflowActivationJob, workflow_activation_job},
         workflow_completion::WorkflowActivationCompletion,
     },
     temporal::api::{
-        enums::v1::EventType, history::v1::WorkflowExecutionOptionsUpdatedEventAttributes,
+        enums::v1::EventType,
+        history::v1::WorkflowExecutionOptionsUpdatedEventAttributes,
+        namespace::v1::{NamespaceInfo, namespace_info::Capabilities},
+        workflowservice::v1::{
+            DescribeNamespaceResponse, PollActivityTaskQueueResponse,
+            RecordActivityTaskHeartbeatResponse,
+        },
     },
 };
-use tokio::{sync::Barrier, time::sleep};
+use temporalio_common::worker::WorkerTaskTypes;
+use tokio::{
+    sync::{Barrier, Notify},
+    time::sleep,
+};
 
 #[tokio::test]
 async fn after_shutdown_server_is_not_polled() {
@@ -111,6 +128,101 @@ async fn shutdown_interrupts_both_polls() {
     };
 }
 
+#[tokio::test]
+async fn graceful_activity_poll_shutdown_handles_unimplemented_shutdown_worker() {
+    let activity_poll_started = Arc::new(Notify::new());
+    let activity_poll_started_clone = activity_poll_started.clone();
+    let shutdown_worker_called = Arc::new(Notify::new());
+    let shutdown_worker_called_clone = shutdown_worker_called.clone();
+
+    let mut mock_client = MockManualWorkerClient::new();
+    mock_client.expect_capabilities().returning(|| None);
+    mock_client
+        .expect_workers()
+        .returning(|| DEFAULT_WORKERS_REGISTRY.clone());
+    mock_client.expect_is_mock().returning(|| true);
+    mock_client
+        .expect_sdk_name_and_version()
+        .returning(|| ("test-core".to_string(), "0.0.0".to_string()));
+    mock_client
+        .expect_identity()
+        .returning(|| "test-identity".to_string());
+    mock_client
+        .expect_worker_grouping_key()
+        .returning(uuid::Uuid::new_v4);
+    mock_client
+        .expect_worker_instance_key()
+        .returning(uuid::Uuid::new_v4);
+    mock_client
+        .expect_describe_namespace()
+        .times(1)
+        .returning(|| {
+            async {
+                Ok(DescribeNamespaceResponse {
+                    namespace_info: Some(NamespaceInfo {
+                        capabilities: Some(Capabilities {
+                            worker_poll_complete_on_shutdown: true,
+                            ..Default::default()
+                        }),
+                        ..Default::default()
+                    }),
+                    ..Default::default()
+                })
+            }
+            .boxed()
+        });
+    mock_client
+        .expect_shutdown_worker()
+        .times(1)
+        .returning(move |_, _, _, _| {
+            let shutdown_worker_called = shutdown_worker_called_clone.clone();
+            async move {
+                shutdown_worker_called.notify_one();
+                Err(tonic::Status::unimplemented(
+                    "ShutdownWorker disabled by server",
+                ))
+            }
+            .boxed()
+        });
+    mock_client
+        .expect_poll_activity_task()
+        .times(1)
+        .returning(move |_, _| {
+            let activity_poll_started = activity_poll_started_clone.clone();
+            async move {
+                activity_poll_started.notify_one();
+                future::pending::<Result<PollActivityTaskQueueResponse, tonic::Status>>().await
+            }
+            .boxed()
+        });
+    mock_client
+        .expect_record_activity_heartbeat()
+        .returning(|_, _| async { Ok(RecordActivityTaskHeartbeatResponse::default()) }.boxed());
+
+    let mut cfg = test_worker_cfg()
+        .activity_task_poller_behavior(PollerBehavior::SimpleMaximum(1_usize))
+        .build()
+        .unwrap();
+    cfg.task_types = WorkerTaskTypes::activity_only();
+    let worker = Worker::new_test(cfg, mock_client);
+    worker.validate().await.unwrap();
+
+    let poll_fut = async { worker.poll_activity_task().await };
+    let shutdown_fut = async {
+        activity_poll_started.notified().await;
+        worker.initiate_shutdown();
+        shutdown_worker_called.notified().await;
+    };
+
+    let (poll_result, _) = tokio::time::timeout(Duration::from_millis(500), async {
+        tokio::join!(poll_fut, shutdown_fut)
+    })
+    .await
+    .expect("activity poll remained pending after shutdown_worker returned UNIMPLEMENTED");
+
+    assert_matches!(poll_result.unwrap_err(), PollError::ShutDown);
+}
+
 #[tokio::test]
 async fn ignores_workflow_options_updated_event() {
     let mut t = TestHistoryBuilder::default();
diff --git a/crates/sdk-core/src/pollers/poll_buffer.rs b/crates/sdk-core/src/pollers/poll_buffer.rs
index a4d1353de..fb2ca0129 100644
--- a/crates/sdk-core/src/pollers/poll_buffer.rs
+++ b/crates/sdk-core/src/pollers/poll_buffer.rs
@@ -387,7 +387,17 @@ where
                     let capabilities = capabilities.clone();
                     let poll_task = tokio::spawn(async move {
                         let r = if capabilities.graceful_poll_shutdown() {
-                            pf(timeout_override).await
+                            let shutdown_for_graceful_fallback = shutdown.clone();
+                            let local_interrupt_after_graceful_disabled = async move {
+                                shutdown_for_graceful_fallback.cancelled().await;
+                                while capabilities.graceful_poll_shutdown() {
+                                    tokio::time::sleep(Duration::from_millis(10)).await;
+                                }
+                            };
+                            tokio::select! {
+                                r = pf(timeout_override) => r,
+                                _ = local_interrupt_after_graceful_disabled => return,
+                            }
                         } else {
                             let poll_interruptor = shutdown.cancelled().then(|_| async move {
                                 if let Some(w) = poll_shutdown_interrupt_wait {
diff --git a/crates/sdk-core/src/worker/mod.rs b/crates/sdk-core/src/worker/mod.rs
index 6082ff77e..063f5b580 100644
--- a/crates/sdk-core/src/worker/mod.rs
+++ b/crates/sdk-core/src/worker/mod.rs
@@ -1439,23 +1439,34 @@ impl Worker {
             .heartbeat_manager
             .as_ref()
             .map(|hm| hm.heartbeat_callback.clone()());
+        let capabilities = self.capabilities.clone();
         let handle = tokio::spawn(async move {
             match client
                 .shutdown_worker(sticky_name, task_queue, task_queue_types, heartbeat)
                 .await
             {
                 Err(err)
-                    if !matches!(
+                    if matches!(
                         err.code(),
                         tonic::Code::Unimplemented | tonic::Code::Unavailable
                     ) =>
                 {
+                    capabilities
+                        .graceful_poll_shutdown
+                        .store(false, Ordering::Relaxed);
+                    debug!(
+                        "shutdown_worker rpc unavailable during worker shutdown; \
+                         disabling graceful poll shutdown and interrupting polls locally: {:?}",
+                        err
+                    );
+                }
+                Err(err) => {
                     warn!(
                         "shutdown_worker rpc errored during worker shutdown: {:?}",
                         err
                     );
                 }
-                _ => {}
+                Ok(_) => {}
             }
         });
         *guard = Some(handle);