diff --git a/javasample/src/main/java/com/oursky/authgeartest/MainActivity.java b/javasample/src/main/java/com/oursky/authgeartest/MainActivity.java
index 6257ee19..8c206c6d 100644
--- a/javasample/src/main/java/com/oursky/authgeartest/MainActivity.java
+++ b/javasample/src/main/java/com/oursky/authgeartest/MainActivity.java
@@ -65,6 +65,7 @@ public class MainActivity extends AppCompatActivity {
     private View mChangePassword;
     private View mDeleteAccount;
     private View mFetchUserInfo;
+    private View mRefreshAccessToken;
     private View mShowAuthTime;
     private View mLogout;
     private MainViewModel viewModel;
@@ -104,6 +105,7 @@ protected void onCreate(Bundle savedInstanceState) {
         mChangePassword = findViewById(R.id.changePassword);
         mDeleteAccount = findViewById(R.id.deleteAccount);
         mFetchUserInfo = findViewById(R.id.fetchUserInfo);
+        mRefreshAccessToken = findViewById(R.id.refreshAccessToken);
         mShowAuthTime = findViewById(R.id.showAuthTime);
         mLogout = findViewById(R.id.logout);
         mUseWebKitWebView = findViewById(R.id.useWebKitWebView);
@@ -167,6 +169,7 @@ protected void onCreate(Bundle savedInstanceState) {
         mChangePassword.setOnClickListener(view -> viewModel.openChangePassword());
         mDeleteAccount.setOnClickListener(view -> viewModel.openDeleteAccount());
         mFetchUserInfo.setOnClickListener(view -> viewModel.fetchUserInfo());
+        mRefreshAccessToken.setOnClickListener(view -> viewModel.refreshAccessToken());
         mShowAuthTime.setOnClickListener(view -> viewModel.showAuthTime(this));
         mLogout.setOnClickListener(view -> viewModel.logout());
 
@@ -264,7 +267,10 @@ public void onNothingSelected(AdapterView<?> parent) {
             mApp2AppstateField.setVisibility(app2appEnabled ? View.VISIBLE : View.GONE);
         });
 
-        viewModel.sessionState().observe(this, sessionState -> mSessionState.setText(viewModel.sessionState().getValue().toString()));
+        viewModel.sessionState().observe(this, sessionState -> {
+            mSessionState.setText(viewModel.sessionState().getValue().toString());
+            updateButtonDisabledState(viewModel);
+        });
 
         viewModel.isLoading().observe(this, isLoading -> updateButtonDisabledState(viewModel));
         viewModel.isBiometricEnabled().observe(this, isEnabled -> updateButtonDisabledState(viewModel));
@@ -280,6 +286,16 @@ public void onNothingSelected(AdapterView<?> parent) {
             builder.create().show();
         });
 
+        viewModel.refreshAccessTokenResult().observe(this, message -> {
+            if (message == null) return;
+            AlertDialog.Builder builder = new AlertDialog.Builder(this);
+            builder.setTitle("Refresh Access Token If Needed");
+            builder.setMessage(message);
+            builder.setPositiveButton("OK", (dialogInterface, i) -> {
+            });
+            builder.create().show();
+        });
+
         viewModel.error().observe(this, e -> {
             if (e == null) return;
             AlertDialog.Builder builder = new AlertDialog.Builder(this);
@@ -358,6 +374,7 @@ private void updateButtonDisabledState(MainViewModel viewModel) {
         mChangePassword.setEnabled(!isLoading && isConfigured && isLoggedIn);
         mDeleteAccount.setEnabled(!isLoading && isConfigured && isLoggedIn);
         mFetchUserInfo.setEnabled(!isLoading && isConfigured && isLoggedIn);
+        mRefreshAccessToken.setEnabled(!isLoading && isConfigured && isLoggedIn);
         mShowAuthTime.setEnabled(!isLoading && isConfigured && isLoggedIn);
         mLogout.setEnabled(!isLoading && isConfigured && isLoggedIn);
     }
diff --git a/javasample/src/main/java/com/oursky/authgeartest/MainViewModel.java b/javasample/src/main/java/com/oursky/authgeartest/MainViewModel.java
index 65cd8b03..1c0a3c4c 100644
--- a/javasample/src/main/java/com/oursky/authgeartest/MainViewModel.java
+++ b/javasample/src/main/java/com/oursky/authgeartest/MainViewModel.java
@@ -29,6 +29,7 @@
 import com.oursky.authgear.CancelException;
 import com.oursky.authgear.ColorScheme;
 import com.oursky.authgear.CustomTabsUIImplementation;
+import com.oursky.authgear.OAuthException;
 import com.oursky.authgear.OnAuthenticateAnonymouslyListener;
 import com.oursky.authgear.OnAuthenticateBiometricListener;
 import com.oursky.authgear.OnAuthenticateListener;
@@ -43,6 +44,7 @@
 import com.oursky.authgear.OnOpenURLListener;
 import com.oursky.authgear.OnPromoteAnonymousUserListener;
 import com.oursky.authgear.OnReauthenticateListener;
+import com.oursky.authgear.OnRefreshAccessTokenIfNeededListener;
 import com.oursky.authgear.OnRefreshIDTokenListener;
 import com.oursky.authgear.OnWechatAuthCallbackListener;
 import com.oursky.authgear.OpenAuthorizationURLOptions;
@@ -99,6 +101,7 @@ public class MainViewModel extends AndroidViewModel implements AuthgearDelegate
     final private MutableLiveData<UserInfo> mUserInfo = new MutableLiveData<>(null);
     final private MutableLiveData<SessionState> mSessionState = new MutableLiveData<>(SessionState.UNKNOWN);
     final private MutableLiveData<Throwable> mError = new MutableLiveData<>(null);
+    final private MutableLiveData<String> mRefreshAccessTokenResult = new MutableLiveData<>(null);
     private Intent pendingApp2AppIntent = null;
     final private MutableLiveData<Boolean> mAuthgearConfigured = new MutableLiveData<>(false);
     final private MutableLiveData<ConfirmationViewModel> mApp2AppConfirmation = new MutableLiveData<>(null);
@@ -239,6 +242,10 @@ public LiveData<UserInfo> userInfo() {
     public LiveData<Throwable> error() {
         return mError;
     }
+
+    public LiveData<String> refreshAccessTokenResult() {
+        return mRefreshAccessTokenResult;
+    }
     public LiveData<ConfirmationViewModel> app2appConfirmation() { return mApp2AppConfirmation; }
 
     public void configure(
@@ -347,8 +354,16 @@ public void onWechatAuthCallbackFailed(Throwable throwable) {
     }
 
     @Override
-    public void onSessionStateChanged(Authgear container, SessionStateChangeReason reason) {
-        Log.d(TAG, "Session state=" + container.getSessionState() + " reason=" + reason);
+    public void onSessionStateChanged(Authgear container, SessionStateChangeReason reason, @Nullable Throwable error) {
+        Log.d(TAG, "Session state=" + container.getSessionState() + " reason=" + reason + " error=" + error);
+        if (error instanceof OAuthException) {
+            String oauthError = ((OAuthException) error).getError();
+            if ("invalid_grant".equals(oauthError)) {
+                Log.d(TAG, "onSessionStateChanged: error is invalid_grant");
+            } else if ("invalid_dpop_proof".equals(oauthError)) {
+                Log.d(TAG, "onSessionStateChanged: error is invalid_dpop_proof");
+            }
+        }
         this.mSessionState.setValue(container.getSessionState());
     }
 
@@ -847,6 +862,26 @@ public void onFetchingUserInfoFailed(@NonNull Throwable throwable) {
         });
     }
 
+    // Unlike fetchUserInfo(), this does NOT chain any follow-up request
+    // after refresh, so the refresh result (e.g. invalid_grant vs
+    // invalid_dpop_proof) is not masked by a subsequent request made with a
+    // stale/missing access token.
+    public void refreshAccessToken() {
+        mAuthgear.refreshAccessTokenIfNeeded(new OnRefreshAccessTokenIfNeededListener() {
+            @Override
+            public void onFinished() {
+                mRefreshAccessTokenResult.setValue(
+                        "Refreshed access token successfully.\nsessionState: " + mAuthgear.getSessionState()
+                );
+            }
+
+            @Override
+            public void onFailed(Throwable throwable) {
+                setError(throwable);
+            }
+        });
+    }
+
     public void showAuthTime(FragmentActivity activity) {
         Date nullable = mAuthgear.getAuthTime();
         if (nullable != null) {
diff --git a/javasample/src/main/res/layout/activity_main.xml b/javasample/src/main/res/layout/activity_main.xml
index b8d0b174..79694d80 100644
--- a/javasample/src/main/res/layout/activity_main.xml
+++ b/javasample/src/main/res/layout/activity_main.xml
@@ -586,6 +586,15 @@
                     android:text="Fetch user info"
                     tools:ignore="HardcodedText" />
 
+                <Button
+                    android:id="@+id/refreshAccessToken"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_marginBottom="16dp"
+                    android:layout_gravity="center_horizontal"
+                    android:text="Refresh Access Token If Needed"
+                    tools:ignore="HardcodedText" />
+
                 <Button
                     android:id="@+id/showAuthTime"
                     android:layout_width="wrap_content"
diff --git a/sdk/src/main/java/com/oursky/authgear/AuthgearCore.kt b/sdk/src/main/java/com/oursky/authgear/AuthgearCore.kt
index 33c7cf23..979be4bc 100644
--- a/sdk/src/main/java/com/oursky/authgear/AuthgearCore.kt
+++ b/sdk/src/main/java/com/oursky/authgear/AuthgearCore.kt
@@ -564,12 +564,12 @@ internal class AuthgearCore(
         clearSession(SessionStateChangeReason.CLEAR)
     }
 
-    private fun updateSessionState(state: SessionState, reason: SessionStateChangeReason) {
+    private fun updateSessionState(state: SessionState, reason: SessionStateChangeReason, error: Throwable? = null) {
         // TODO: Add re-entry detection
         sessionState = state
         val handler = Handler(Looper.getMainLooper())
         handler.post {
-            this.delegate?.onSessionStateChanged(this.authgear, reason)
+            this.delegate?.onSessionStateChanged(this.authgear, reason, error)
         }
     }
 
@@ -670,7 +670,7 @@ internal class AuthgearCore(
             )
         } catch (e: Exception) {
             handleInvalidGrantError(e)
-            if (e is OAuthException && e.error == "invalid_grant") {
+            if (e is OAuthException && (e.error == "invalid_grant" || e.error == "invalid_dpop_proof")) {
                 return
             }
             throw e
@@ -709,7 +709,7 @@ internal class AuthgearCore(
         }
     }
 
-    internal fun clearSession(changeReason: SessionStateChangeReason) {
+    internal fun clearSession(changeReason: SessionStateChangeReason, error: Throwable? = null) {
         tokenStorage.deleteRefreshToken(name)
         sharedStorage.onLogout(name)
         storage.deleteApp2AppDeviceKeyId(name)
@@ -718,7 +718,7 @@ internal class AuthgearCore(
             refreshToken = null
             idToken = null
             expireAt = null
-            updateSessionState(SessionState.NO_SESSION, changeReason)
+            updateSessionState(SessionState.NO_SESSION, changeReason, error)
         }
     }
 
@@ -876,11 +876,11 @@ internal class AuthgearCore(
     }
 
     private fun handleInvalidGrantError(e: Exception) {
-        if (e is OAuthException && e.error == "invalid_grant") {
-            clearSession(SessionStateChangeReason.INVALID)
+        if (e is OAuthException && (e.error == "invalid_grant" || e.error == "invalid_dpop_proof")) {
+            clearSession(SessionStateChangeReason.INVALID, e)
             return
         } else if (e is ServerException && e.reason == "InvalidGrant") {
-            clearSession(SessionStateChangeReason.INVALID)
+            clearSession(SessionStateChangeReason.INVALID, e)
             return
         }
     }
diff --git a/sdk/src/main/java/com/oursky/authgear/AuthgearDelegate.kt b/sdk/src/main/java/com/oursky/authgear/AuthgearDelegate.kt
index 17b3cdd7..569489ef 100644
--- a/sdk/src/main/java/com/oursky/authgear/AuthgearDelegate.kt
+++ b/sdk/src/main/java/com/oursky/authgear/AuthgearDelegate.kt
@@ -1,7 +1,10 @@
 package com.oursky.authgear
 
 interface AuthgearDelegate {
-    fun onSessionStateChanged(container: Authgear, reason: SessionStateChangeReason) {}
+    // error is non-null when reason is INVALID, i.e. the session was cleared
+    // because a request failed with an error such as invalid_grant or
+    // invalid_dpop_proof. It is null for all other reasons.
+    fun onSessionStateChanged(container: Authgear, reason: SessionStateChangeReason, error: Throwable?) {}
 
     fun sendWechatAuthRequest(state: String) {}
 }