diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2ddaf37..4ba1b70 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -155,3 +155,15 @@ Consequences:
   parentheses and modifiers removed, empty catch blocks named and commented, and two loops
   restructured. The only signature change is the removal of the unused `target` parameter from the
   `CipherGen` constructor (an internal NTLM helper).
+
+### Fixed
+
+- **Streaming terminals now report protocol failures as `WinRMClientException`** (#188).
+  `WqlRequest.stream()`, `CommandRequest.start()`, `RemoteFile.openStream()`/`openReader()`,
+  `RemoteDirectoryListing.stream()` and the closing of a `RemoteProcess` let raw
+  `IllegalStateException`s escape for an unexpected HTTP status (e.g. a 503 from a proxy), an
+  authentication fallback that exhausted every scheme, or a malformed response. They are now
+  wrapped like the blocking terminals' failures, with the raw exception in the cause chain; the
+  typed exceptions (`WinRMFaultException`, `WinRMAuthenticationException`, `WinRMTimeoutException`)
+  pass through unchanged, and genuine caller errors (invalid options, closed client, input after
+  the end of stdin) stay `IllegalArgumentException` / `IllegalStateException`.
diff --git a/src/main/java/org/metricshub/winrm/light/LightWinRMService.java b/src/main/java/org/metricshub/winrm/light/LightWinRMService.java
index 3d8ce84..4e977b7 100644
--- a/src/main/java/org/metricshub/winrm/light/LightWinRMService.java
+++ b/src/main/java/org/metricshub/winrm/light/LightWinRMService.java
@@ -517,6 +517,8 @@ private Chunk adapt(final WsmanClient.RemoteCommand.Chunk chunk) {
 
 			@Override
 			public void send(final byte[] data, final boolean end) throws TimeoutException, WindowsRemoteException {
+				// A caller bug (input after the end mark), reported as such before any protocol step.
+				remoteCommand.checkStdinOpen();
 				callStreaming(() -> {
 					remoteCommand.send(data, end);
 					return null;
@@ -540,7 +542,7 @@ public int exitCode() {
 			public void close() {
 				try {
 					remoteCommand.close();
-				} catch (final RuntimeException e) {
+				} catch (final WinRMClientException e) {
 					// Typed protocol failures (e.g. a fault answering the terminate Signal) pass through.
 					throw e;
 				} catch (final InterruptedException e) {
@@ -564,13 +566,17 @@ public void close() {
 	 * @param step the protocol step to run
 	 * @param <T> the step's result type
 	 * @return the step's result
+	 * @throws IllegalStateException when this executor was closed: a handle outliving its client is a
+	 *         caller bug, reported as such rather than as a protocol failure
 	 * @throws TimeoutException when the step exceeds the inactivity timeout
-	 * @throws WinRMException when the step fails with a checked failure
+	 * @throws WinRMException when the step fails, with the raw failure as its cause — the typed
+	 *         {@link WinRMClientException}s pass through unchanged
 	 */
-	private static <T> T callStreaming(final Callable<T> step) throws TimeoutException, WinRMException {
+	private <T> T callStreaming(final Callable<T> step) throws TimeoutException, WinRMException {
+		checkNotClosed();
 		try {
 			return step.call();
-		} catch (final TimeoutException | RuntimeException e) {
+		} catch (final TimeoutException | WinRMClientException e) {
 			throw e;
 		} catch (final InterruptedException e) {
 			Thread.currentThread().interrupt();
diff --git a/src/main/java/org/metricshub/winrm/light/WsmanClient.java b/src/main/java/org/metricshub/winrm/light/WsmanClient.java
index 006be1b..290a313 100644
--- a/src/main/java/org/metricshub/winrm/light/WsmanClient.java
+++ b/src/main/java/org/metricshub/winrm/light/WsmanClient.java
@@ -736,6 +736,21 @@ Chunk pollChunk(final long askMs, final long maxWaitMs) throws Exception {
 			}
 		}
 
+		/**
+		 * Reject input once the command's standard input is closed: a caller bug, reported before any
+		 * protocol step.
+		 *
+		 * @throws IllegalStateException when the command has completed or its input was ended
+		 */
+		void checkStdinOpen() {
+			if (finished || exitCode != null) {
+				throw new IllegalStateException("The command has completed: its standard input is closed.");
+			}
+			if (stdinEnded) {
+				throw new IllegalStateException("The command's standard input has already been closed.");
+			}
+		}
+
 		/**
 		 * Feed standard input to the running command: one or more WSMan Send requests carrying the
 		 * bytes as base64 {@code stdin} streams, the last one flagged {@code End} when {@code end} is
@@ -755,12 +770,7 @@ Chunk pollChunk(final long askMs, final long maxWaitMs) throws Exception {
 		 * @param end whether this is the last input the command will get
 		 */
 		void send(final byte[] data, final boolean end) throws Exception {
-			if (finished || exitCode != null) {
-				throw new IllegalStateException("The command has completed: its standard input is closed.");
-			}
-			if (stdinEnded) {
-				throw new IllegalStateException("The command's standard input has already been closed.");
-			}
+			checkStdinOpen();
 			if (data.length == 0 && !end) {
 				// Nothing to say and no EOF to announce: an empty Send would be a pure round trip.
 				return;
diff --git a/src/test/java/org/metricshub/winrm/StreamingApiTest.java b/src/test/java/org/metricshub/winrm/StreamingApiTest.java
index a3e366b..831a360 100644
--- a/src/test/java/org/metricshub/winrm/StreamingApiTest.java
+++ b/src/test/java/org/metricshub/winrm/StreamingApiTest.java
@@ -47,6 +47,7 @@
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.metricshub.winrm.exceptions.WinRMClientException;
 import org.metricshub.winrm.exceptions.WinRMTimeoutException;
 import org.metricshub.winrm.exceptions.WqlSyntaxException;
 import org.metricshub.winrm.light.FakeWsmanServer;
@@ -300,6 +301,67 @@ private static String stderrChunk(final String text) {
 		return stream("stderr", COMMAND_ID, text.getBytes(StandardCharsets.UTF_8));
 	}
 
+	private static Throwable rootCause(final Throwable e) {
+		Throwable cause = e;
+		while (cause.getCause() != null) {
+			cause = cause.getCause();
+		}
+		return cause;
+	}
+
+	@Test
+	void streamOutlivingItsClientFailsAsAClosedClient() throws Exception {
+		server.enqueue(200, envelope(enumeratePage("uuid:CTX-1", service("Spooler", "Running"))));
+
+		final WinRMClient client = builder().build();
+		final Iterator<WqlRow> iterator = client.wql("SELECT Name FROM Win32_Service").stream().iterator();
+		assertEquals("Spooler", iterator.next().string("Name"));
+		client.close();
+
+		// The next row needs a Pull on a closed client: a caller bug, not a protocol failure.
+		final IllegalStateException e = assertThrows(IllegalStateException.class, iterator::next);
+		assertEquals("This instance has been closed and a new one must be created.", e.getMessage());
+	}
+
+	@Test
+	void streamReportsAnUnexpectedHttpStatusAsAClientException() {
+		// A 503 from a proxy, or a non-WinRM service on the port: a protocol failure, not a caller bug.
+		server.enqueue(503, fault("999", "Service unavailable"));
+
+		try (WinRMClient client = builder().build()) {
+			final WinRMClientException e = assertThrows(
+				WinRMClientException.class,
+				() -> client.wql("SELECT Name FROM Win32_Service").stream()
+			);
+			assertTrue(e.getMessage().contains("HTTP 503"), e.getMessage());
+			assertTrue(rootCause(e) instanceof IllegalStateException);
+		}
+	}
+
+	@Test
+	void startReportsAnUnexpectedHttpStatusAsAClientException() {
+		server.enqueue(503, fault("999", "Service unavailable"));
+
+		try (WinRMClient client = builder().build()) {
+			final WinRMClientException e = assertThrows(WinRMClientException.class, () -> client.command("dir").start());
+			assertTrue(e.getMessage().contains("HTTP 503"), e.getMessage());
+			assertTrue(rootCause(e) instanceof IllegalStateException);
+		}
+	}
+
+	@Test
+	void closeReportsAnUnexpectedHttpStatusAsAClientException() throws Exception {
+		enqueueCommandStartup();
+		// The terminate Signal of an early close is answered with a 503.
+		server.enqueue(503, fault("999", "Service unavailable"));
+
+		try (WinRMClient client = builder().build()) {
+			final RemoteProcess process = client.command("dir").start();
+			final WinRMClientException e = assertThrows(WinRMClientException.class, process::close);
+			assertTrue(e.getMessage().contains("HTTP 503"), e.getMessage());
+		}
+	}
+
 	@Test
 	void startStreamsOutputWhileTheCommandIsStillRunning() throws Exception {
 		enqueueCommandStartup();