diff --git a/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/IContextHub.aidl b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/IContextHub.aidl
index facce4b..f0676be 100644
--- a/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/IContextHub.aidl
+++ b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/IContextHub.aidl
@@ -35,14 +35,15 @@
 @VintfStability
 interface IContextHub {
   List<android.hardware.contexthub.ContextHubInfo> getContextHubs();
-  boolean loadNanoapp(in int contextHubId, in android.hardware.contexthub.NanoappBinary appBinary, in int transactionId);
-  boolean unloadNanoapp(in int contextHubId, in long appId, in int transactionId);
-  boolean disableNanoapp(in int contextHubId, in long appId, in int transactionId);
-  boolean enableNanoapp(in int contextHubId, in long appId, in int transactionId);
+  void loadNanoapp(in int contextHubId, in android.hardware.contexthub.NanoappBinary appBinary, in int transactionId);
+  void unloadNanoapp(in int contextHubId, in long appId, in int transactionId);
+  void disableNanoapp(in int contextHubId, in long appId, in int transactionId);
+  void enableNanoapp(in int contextHubId, in long appId, in int transactionId);
   void onSettingChanged(in android.hardware.contexthub.Setting setting, in boolean enabled);
-  boolean queryNanoapps(in int contextHubId);
-  boolean registerCallback(in int contextHubId, in android.hardware.contexthub.IContextHubCallback cb);
-  boolean sendMessageToHub(in int contextHubId, in android.hardware.contexthub.ContextHubMessage message);
+  void queryNanoapps(in int contextHubId);
+  void registerCallback(in int contextHubId, in android.hardware.contexthub.IContextHubCallback cb);
+  void sendMessageToHub(in int contextHubId, in android.hardware.contexthub.ContextHubMessage message);
   void onHostEndpointConnected(in android.hardware.contexthub.HostEndpointInfo hostEndpointInfo);
   void onHostEndpointDisconnected(char hostEndpointId);
+  const int EX_CONTEXT_HUB_UNSPECIFIED = -1;
 }
diff --git a/contexthub/aidl/android/hardware/contexthub/IContextHub.aidl b/contexthub/aidl/android/hardware/contexthub/IContextHub.aidl
index 33d241a..2135041 100644
--- a/contexthub/aidl/android/hardware/contexthub/IContextHub.aidl
+++ b/contexthub/aidl/android/hardware/contexthub/IContextHub.aidl
@@ -52,9 +52,12 @@
      * @param appBinary The nanoapp binary with header
      * @param transactionId The transaction ID associated with this request
      *
-     * @return The return code
+     * @throws EX_ILLEGAL_ARGUMENT if any of the arguments are invalid.
+     *         EX_UNSUPPORTED_OPERATION if this functionality is unsupported.
+     *         EX_SERVICE_SPECIFIC on error
+     *         - EX_CONTEXT_HUB_UNSPECIFIED if the request failed for other reasons.
      */
-    boolean loadNanoapp(in int contextHubId, in NanoappBinary appBinary, in int transactionId);
+    void loadNanoapp(in int contextHubId, in NanoappBinary appBinary, in int transactionId);
 
     /**
      * Invokes the nanoapp's deinitialization "end()" entrypoint, and unloads the nanoapp.
@@ -69,9 +72,12 @@
      * @param appId The unique ID of the nanoapp
      * @param transactionId The transaction ID associated with this request
      *
-     * @return The return code
+     * @throws EX_ILLEGAL_ARGUMENT if any of the arguments are invalid.
+     *         EX_UNSUPPORTED_OPERATION if this functionality is unsupported.
+     *         EX_SERVICE_SPECIFIC on error
+     *         - EX_CONTEXT_HUB_UNSPECIFIED if the request failed for other reasons.
      */
-    boolean unloadNanoapp(in int contextHubId, in long appId, in int transactionId);
+    void unloadNanoapp(in int contextHubId, in long appId, in int transactionId);
 
     /**
      * Disables a nanoapp by invoking the nanoapp's "end()" entrypoint, but does not unload the
@@ -87,9 +93,12 @@
      * @param appId The unique ID of the nanoapp
      * @param transactionId The transaction ID associated with this request
      *
-     * @return The return code
+     * @throws EX_ILLEGAL_ARGUMENT if any of the arguments are invalid.
+     *         EX_UNSUPPORTED_OPERATION if this functionality is unsupported.
+     *         EX_SERVICE_SPECIFIC on error
+     *         - EX_CONTEXT_HUB_UNSPECIFIED if the request failed for other reasons.
      */
-    boolean disableNanoapp(in int contextHubId, in long appId, in int transactionId);
+    void disableNanoapp(in int contextHubId, in long appId, in int transactionId);
 
     /**
      * Enables a nanoapp by invoking the nanoapp's initialization "start()" entrypoint.
@@ -104,9 +113,12 @@
      * @param appId appIdentifier returned by the HAL
      * @param message   message to be sent
      *
-     * @return true on success
+     * @throws EX_ILLEGAL_ARGUMENT if any of the arguments are invalid.
+     *         EX_UNSUPPORTED_OPERATION if this functionality is unsupported.
+     *         EX_SERVICE_SPECIFIC on error
+     *         - EX_CONTEXT_HUB_UNSPECIFIED if the request failed for other reasons.
      */
-    boolean enableNanoapp(in int contextHubId, in long appId, in int transactionId);
+    void enableNanoapp(in int contextHubId, in long appId, in int transactionId);
 
     /**
      * Notification sent by the framework to indicate that the user has changed a setting.
@@ -124,9 +136,12 @@
      *
      * @param contextHubId The identifier of the Context Hub
      *
-     * @return true on success
+     * @throws EX_ILLEGAL_ARGUMENT if any of the arguments are invalid.
+     *         EX_UNSUPPORTED_OPERATION if this functionality is unsupported.
+     *         EX_SERVICE_SPECIFIC on error
+     *         - EX_CONTEXT_HUB_UNSPECIFIED if the request failed for other reasons.
      */
-    boolean queryNanoapps(in int contextHubId);
+    void queryNanoapps(in int contextHubId);
 
     /**
      * Register a callback for the HAL implementation to send asynchronous messages to the service
@@ -138,10 +153,11 @@
      * @param contextHubId The identifier of the Context Hub
      * @param callback an implementation of the IContextHubCallbacks
      *
-     * @return true on success
-     *
+     * @throws EX_ILLEGAL_ARGUMENT if any of the arguments are invalid.
+     *         EX_SERVICE_SPECIFIC on error
+     *         - EX_CONTEXT_HUB_UNSPECIFIED if the request failed for other reasons.
      */
-    boolean registerCallback(in int contextHubId, in IContextHubCallback cb);
+    void registerCallback(in int contextHubId, in IContextHubCallback cb);
 
     /**
      * Sends a message targeted to a nanoapp to the Context Hub.
@@ -149,9 +165,11 @@
      * @param contextHubId The identifier of the Context Hub
      * @param message The message to be sent
      *
-     * @return true on success
+     * @throws EX_ILLEGAL_ARGUMENT if any of the arguments are invalid.
+     *         EX_SERVICE_SPECIFIC on error
+     *         - EX_CONTEXT_HUB_UNSPECIFIED if the request failed for other reasons.
      */
-    boolean sendMessageToHub(in int contextHubId, in ContextHubMessage message);
+    void sendMessageToHub(in int contextHubId, in ContextHubMessage message);
 
     /**
      * Invoked when a host endpoint has connected with the ContextHubService.
@@ -173,8 +191,13 @@
      *
      * @param hostEndPointId The ID of the host that has disconnected.
      *
-     * @return Status::ok on success
-     *         EX_ILLEGAL_ARGUMENT if hostEndpointId is not associated with a connected host.
+     * @throws EX_ILLEGAL_ARGUMENT if hostEndpointId is not associated with a connected host.
      */
     void onHostEndpointDisconnected(char hostEndpointId);
+
+    /**
+     * Error codes that are used as service specific errors with the AIDL return
+     * value EX_SERVICE_SPECIFIC.
+     */
+    const int EX_CONTEXT_HUB_UNSPECIFIED = -1;
 }
diff --git a/contexthub/aidl/default/ContextHub.cpp b/contexthub/aidl/default/ContextHub.cpp
index 6da690d..4c23cbc 100644
--- a/contexthub/aidl/default/ContextHub.cpp
+++ b/contexthub/aidl/default/ContextHub.cpp
@@ -21,7 +21,9 @@
 namespace hardware {
 namespace contexthub {
 
-::ndk::ScopedAStatus ContextHub::getContextHubs(std::vector<ContextHubInfo>* out_contextHubInfos) {
+using ::ndk::ScopedAStatus;
+
+ScopedAStatus ContextHub::getContextHubs(std::vector<ContextHubInfo>* out_contextHubInfos) {
     ContextHubInfo hub = {};
     hub.name = "Mock Context Hub";
     hub.vendor = "AOSP";
@@ -39,85 +41,70 @@
 }
 
 // We don't expose any nanoapps for the default impl, therefore all nanoapp-related APIs fail.
-::ndk::ScopedAStatus ContextHub::loadNanoapp(int32_t /* in_contextHubId */,
-                                             const NanoappBinary& /* in_appBinary */,
-                                             int32_t /* in_transactionId */, bool* _aidl_return) {
-    *_aidl_return = false;
+ScopedAStatus ContextHub::loadNanoapp(int32_t /* in_contextHubId */,
+                                      const NanoappBinary& /* in_appBinary */,
+                                      int32_t /* in_transactionId */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+}
+
+ScopedAStatus ContextHub::unloadNanoapp(int32_t /* in_contextHubId */, int64_t /* in_appId */,
+                                        int32_t /* in_transactionId */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+}
+
+ScopedAStatus ContextHub::disableNanoapp(int32_t /* in_contextHubId */, int64_t /* in_appId */,
+                                         int32_t /* in_transactionId */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+}
+
+ScopedAStatus ContextHub::enableNanoapp(int32_t /* in_contextHubId */, int64_t /* in_appId */,
+                                        int32_t /* in_transactionId */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+}
+
+ScopedAStatus ContextHub::onSettingChanged(Setting /* in_setting */, bool /*in_enabled */) {
     return ndk::ScopedAStatus::ok();
 }
 
-::ndk::ScopedAStatus ContextHub::unloadNanoapp(int32_t /* in_contextHubId */,
-                                               int64_t /* in_appId */,
-                                               int32_t /* in_transactionId */, bool* _aidl_return) {
-    *_aidl_return = false;
-    return ndk::ScopedAStatus::ok();
-}
-
-::ndk::ScopedAStatus ContextHub::disableNanoapp(int32_t /* in_contextHubId */,
-                                                int64_t /* in_appId */,
-                                                int32_t /* in_transactionId */,
-                                                bool* _aidl_return) {
-    *_aidl_return = false;
-    return ndk::ScopedAStatus::ok();
-}
-
-::ndk::ScopedAStatus ContextHub::enableNanoapp(int32_t /* in_contextHubId */,
-                                               int64_t /* in_appId */,
-                                               int32_t /* in_transactionId */, bool* _aidl_return) {
-    *_aidl_return = false;
-    return ndk::ScopedAStatus::ok();
-}
-
-::ndk::ScopedAStatus ContextHub::onSettingChanged(Setting /* in_setting */, bool /*in_enabled */) {
-    return ndk::ScopedAStatus::ok();
-}
-
-::ndk::ScopedAStatus ContextHub::queryNanoapps(int32_t in_contextHubId, bool* _aidl_return) {
+ScopedAStatus ContextHub::queryNanoapps(int32_t in_contextHubId) {
     if (in_contextHubId == kMockHubId && mCallback != nullptr) {
         std::vector<NanoappInfo> nanoapps;
         mCallback->handleNanoappInfo(nanoapps);
-        *_aidl_return = true;
+        return ndk::ScopedAStatus::ok();
     } else {
-        *_aidl_return = false;
+        return ScopedAStatus::fromExceptionCode(EX_ILLEGAL_ARGUMENT);
     }
-
-    return ndk::ScopedAStatus::ok();
 }
 
-::ndk::ScopedAStatus ContextHub::registerCallback(int32_t in_contextHubId,
-                                                  const std::shared_ptr<IContextHubCallback>& in_cb,
-                                                  bool* _aidl_return) {
+ScopedAStatus ContextHub::registerCallback(int32_t in_contextHubId,
+                                           const std::shared_ptr<IContextHubCallback>& in_cb) {
     if (in_contextHubId == kMockHubId) {
         mCallback = in_cb;
-        *_aidl_return = true;
+        return ndk::ScopedAStatus::ok();
     } else {
-        *_aidl_return = false;
+        return ScopedAStatus::fromExceptionCode(EX_ILLEGAL_ARGUMENT);
     }
-    return ndk::ScopedAStatus::ok();
 }
 
-::ndk::ScopedAStatus ContextHub::sendMessageToHub(int32_t in_contextHubId,
-                                                  const ContextHubMessage& /* in_message */,
-                                                  bool* _aidl_return) {
+ScopedAStatus ContextHub::sendMessageToHub(int32_t in_contextHubId,
+                                           const ContextHubMessage& /* in_message */) {
     if (in_contextHubId == kMockHubId) {
         // Return true here to indicate that the HAL has accepted the message.
         // Successful delivery of the message to a nanoapp should be handled at
         // a higher level protocol.
-        *_aidl_return = true;
+        return ndk::ScopedAStatus::ok();
     } else {
-        *_aidl_return = false;
+        return ScopedAStatus::fromExceptionCode(EX_ILLEGAL_ARGUMENT);
     }
-
-    return ndk::ScopedAStatus::ok();
 }
 
-::ndk::ScopedAStatus ContextHub::onHostEndpointConnected(const HostEndpointInfo& in_info) {
+ScopedAStatus ContextHub::onHostEndpointConnected(const HostEndpointInfo& in_info) {
     mConnectedHostEndpoints.insert(in_info.hostEndpointId);
 
     return ndk::ScopedAStatus::ok();
 }
 
-::ndk::ScopedAStatus ContextHub::onHostEndpointDisconnected(char16_t in_hostEndpointId) {
+ScopedAStatus ContextHub::onHostEndpointDisconnected(char16_t in_hostEndpointId) {
     if (mConnectedHostEndpoints.count(in_hostEndpointId) > 0) {
         mConnectedHostEndpoints.erase(in_hostEndpointId);
         return ndk::ScopedAStatus::ok();
diff --git a/contexthub/aidl/default/include/contexthub-impl/ContextHub.h b/contexthub/aidl/default/include/contexthub-impl/ContextHub.h
index dd739e6..03d8432 100644
--- a/contexthub/aidl/default/include/contexthub-impl/ContextHub.h
+++ b/contexthub/aidl/default/include/contexthub-impl/ContextHub.h
@@ -28,21 +28,19 @@
 class ContextHub : public BnContextHub {
     ::ndk::ScopedAStatus getContextHubs(std::vector<ContextHubInfo>* out_contextHubInfos) override;
     ::ndk::ScopedAStatus loadNanoapp(int32_t in_contextHubId, const NanoappBinary& in_appBinary,
-                                     int32_t in_transactionId, bool* _aidl_return) override;
+                                     int32_t in_transactionId) override;
     ::ndk::ScopedAStatus unloadNanoapp(int32_t in_contextHubId, int64_t in_appId,
-                                       int32_t in_transactionId, bool* _aidl_return) override;
+                                       int32_t in_transactionId) override;
     ::ndk::ScopedAStatus disableNanoapp(int32_t in_contextHubId, int64_t in_appId,
-                                        int32_t in_transactionId, bool* _aidl_return) override;
+                                        int32_t in_transactionId) override;
     ::ndk::ScopedAStatus enableNanoapp(int32_t in_contextHubId, int64_t in_appId,
-                                       int32_t in_transactionId, bool* _aidl_return) override;
+                                       int32_t in_transactionId) override;
     ::ndk::ScopedAStatus onSettingChanged(Setting in_setting, bool in_enabled) override;
-    ::ndk::ScopedAStatus queryNanoapps(int32_t in_contextHubId, bool* _aidl_return) override;
-    ::ndk::ScopedAStatus registerCallback(int32_t in_contextHubId,
-                                          const std::shared_ptr<IContextHubCallback>& in_cb,
-                                          bool* _aidl_return) override;
+    ::ndk::ScopedAStatus queryNanoapps(int32_t in_contextHubId) override;
+    ::ndk::ScopedAStatus registerCallback(
+            int32_t in_contextHubId, const std::shared_ptr<IContextHubCallback>& in_cb) override;
     ::ndk::ScopedAStatus sendMessageToHub(int32_t in_contextHubId,
-                                          const ContextHubMessage& in_message,
-                                          bool* _aidl_return) override;
+                                          const ContextHubMessage& in_message) override;
     ::ndk::ScopedAStatus onHostEndpointConnected(const HostEndpointInfo& in_info) override;
 
     ::ndk::ScopedAStatus onHostEndpointDisconnected(char16_t in_hostEndpointId) override;
diff --git a/contexthub/aidl/vts/VtsAidlHalContextHubTargetTest.cpp b/contexthub/aidl/vts/VtsAidlHalContextHubTargetTest.cpp
index 392e23c..a47f64e 100644
--- a/contexthub/aidl/vts/VtsAidlHalContextHubTargetTest.cpp
+++ b/contexthub/aidl/vts/VtsAidlHalContextHubTargetTest.cpp
@@ -103,15 +103,12 @@
 };
 
 TEST_P(ContextHubAidl, TestRegisterCallback) {
-    bool success;
     sp<EmptyContextHubCallback> cb = sp<EmptyContextHubCallback>::make();
-    ASSERT_TRUE(contextHub->registerCallback(getHubId(), cb, &success).isOk());
-    ASSERT_TRUE(success);
+    ASSERT_TRUE(contextHub->registerCallback(getHubId(), cb).isOk());
 }
 
 TEST_P(ContextHubAidl, TestRegisterNullCallback) {
-    bool success;
-    ASSERT_TRUE(contextHub->registerCallback(getHubId(), nullptr, &success).isOk());
+    ASSERT_TRUE(contextHub->registerCallback(getHubId(), nullptr).isOk());
 }
 
 // Helper callback that puts the async appInfo callback data into a promise
@@ -140,12 +137,8 @@
 // Calls queryApps() and checks the returned metadata
 TEST_P(ContextHubAidl, TestQueryApps) {
     sp<QueryAppsCallback> cb = sp<QueryAppsCallback>::make();
-    bool success;
-    ASSERT_TRUE(contextHub->registerCallback(getHubId(), cb, &success).isOk());
-    ASSERT_TRUE(success);
-
-    ASSERT_TRUE(contextHub->queryNanoapps(getHubId(), &success).isOk());
-    ASSERT_TRUE(success);
+    ASSERT_TRUE(contextHub->registerCallback(getHubId(), cb).isOk());
+    ASSERT_TRUE(contextHub->queryNanoapps(getHubId()).isOk());
 
     std::vector<NanoappInfo> appInfoList;
     ASSERT_TRUE(waitForCallback(cb->promise.get_future(), &appInfoList));
@@ -197,9 +190,7 @@
   public:
     virtual void SetUp() override {
         ContextHubAidl::SetUp();
-        bool success;
-        ASSERT_TRUE(contextHub->registerCallback(getHubId(), cb, &success).isOk());
-        ASSERT_TRUE(success);
+        ASSERT_TRUE(contextHub->registerCallback(getHubId(), cb).isOk());
     }
 
     sp<TransactionResultCallback> cb = sp<TransactionResultCallback>::make();
@@ -213,9 +204,7 @@
     std::fill(message.messageBody.begin(), message.messageBody.end(), 0);
 
     ALOGD("Sending message to non-existent nanoapp");
-    bool success;
-    ASSERT_TRUE(contextHub->sendMessageToHub(getHubId(), message, &success).isOk());
-    ASSERT_TRUE(success);
+    ASSERT_TRUE(contextHub->sendMessageToHub(getHubId(), message).isOk());
 }
 
 TEST_P(ContextHubTransactionTest, TestLoadEmptyNanoapp) {
@@ -229,9 +218,7 @@
     emptyApp.targetChreApiMinorVersion = 0;
 
     ALOGD("Loading empty nanoapp");
-    bool success;
-    ASSERT_TRUE(contextHub->loadNanoapp(getHubId(), emptyApp, cb->expectedTransactionId, &success)
-                        .isOk());
+    bool success = contextHub->loadNanoapp(getHubId(), emptyApp, cb->expectedTransactionId).isOk();
     if (success) {
         bool transactionSuccess;
         ASSERT_TRUE(waitForCallback(cb->promise.get_future(), &transactionSuccess));
@@ -243,11 +230,9 @@
     cb->expectedTransactionId = 1234;
 
     ALOGD("Unloading nonexistent nanoapp");
-    bool success;
-    ASSERT_TRUE(contextHub
-                        ->unloadNanoapp(getHubId(), kNonExistentAppId, cb->expectedTransactionId,
-                                        &success)
-                        .isOk());
+    bool success =
+            contextHub->unloadNanoapp(getHubId(), kNonExistentAppId, cb->expectedTransactionId)
+                    .isOk();
     if (success) {
         bool transactionSuccess;
         ASSERT_TRUE(waitForCallback(cb->promise.get_future(), &transactionSuccess));
@@ -259,11 +244,9 @@
     cb->expectedTransactionId = 2345;
 
     ALOGD("Enabling nonexistent nanoapp");
-    bool success;
-    ASSERT_TRUE(contextHub
-                        ->enableNanoapp(getHubId(), kNonExistentAppId, cb->expectedTransactionId,
-                                        &success)
-                        .isOk());
+    bool success =
+            contextHub->enableNanoapp(getHubId(), kNonExistentAppId, cb->expectedTransactionId)
+                    .isOk();
     if (success) {
         bool transactionSuccess;
         ASSERT_TRUE(waitForCallback(cb->promise.get_future(), &transactionSuccess));
@@ -275,11 +258,9 @@
     cb->expectedTransactionId = 3456;
 
     ALOGD("Disabling nonexistent nanoapp");
-    bool success;
-    ASSERT_TRUE(contextHub
-                        ->disableNanoapp(getHubId(), kNonExistentAppId, cb->expectedTransactionId,
-                                         &success)
-                        .isOk());
+    bool success =
+            contextHub->disableNanoapp(getHubId(), kNonExistentAppId, cb->expectedTransactionId)
+                    .isOk();
     if (success) {
         bool transactionSuccess;
         ASSERT_TRUE(waitForCallback(cb->promise.get_future(), &transactionSuccess));
@@ -290,16 +271,13 @@
 void ContextHubAidl::testSettingChanged(Setting setting) {
     // In VTS, we only test that sending the values doesn't cause things to blow up - GTS tests
     // verify the expected E2E behavior in CHRE
-    bool success;
     sp<EmptyContextHubCallback> cb = sp<EmptyContextHubCallback>::make();
-    ASSERT_TRUE(contextHub->registerCallback(getHubId(), cb, &success).isOk());
-    ASSERT_TRUE(success);
+    ASSERT_TRUE(contextHub->registerCallback(getHubId(), cb).isOk());
 
     ASSERT_TRUE(contextHub->onSettingChanged(setting, true /* enabled */).isOk());
     ASSERT_TRUE(contextHub->onSettingChanged(setting, false /* enabled */).isOk());
 
-    ASSERT_TRUE(contextHub->registerCallback(getHubId(), nullptr, &success).isOk());
-    ASSERT_TRUE(success);
+    ASSERT_TRUE(contextHub->registerCallback(getHubId(), nullptr).isOk());
 }
 
 TEST_P(ContextHubAidl, TestOnLocationSettingChanged) {