diff --git a/src/main/java/com/qingstor/sdk/exception/QSException.java b/src/main/java/com/qingstor/sdk/exception/QSException.java
index 12b3795c..98745693 100644
--- a/src/main/java/com/qingstor/sdk/exception/QSException.java
+++ b/src/main/java/com/qingstor/sdk/exception/QSException.java
@@ -25,6 +25,10 @@ public class QSException extends Exception {
 
     private String errorMessage;
 
+    public QSException(Throwable t) {
+        super(t);
+    }
+
     public QSException(String message, Throwable t) {
         super(message, t);
     }
@@ -60,9 +64,16 @@ public void setErrorMessage(String errorMessage) {
     @Override
     public String getMessage() {
         String cause = super.getMessage();
-        if (getCause() != null) {
+        if (cause == null && getCause() != null) {
+            cause =
+                    getCause().getMessage() != null
+                            ? getCause().getMessage()
+                            : getCause().toString();
+        } else if (cause != null && getCause() != null && getCause().getMessage() != null) {
             cause += "\n" + getCause().getMessage();
         }
-        return String.format("Error Code: %s; Error Message: %s", getErrorCode(), cause);
+        return String.format(
+                "Error Code: %s; Error Message: %s",
+                getErrorCode(), cause != null ? cause : "Unknown");
     }
 }
diff --git a/src/main/java/com/qingstor/sdk/request/QSOkHttpRequestClient.java b/src/main/java/com/qingstor/sdk/request/QSOkHttpRequestClient.java
index 563e9d9a..a29fb07a 100644
--- a/src/main/java/com/qingstor/sdk/request/QSOkHttpRequestClient.java
+++ b/src/main/java/com/qingstor/sdk/request/QSOkHttpRequestClient.java
@@ -75,9 +75,10 @@ public <T extends OutputModel> T requestAction(
                         QSConstant.REQUEST_ERROR_CANCELLED, e.getMessage(), model);
                 return model;
             } else {
-                e.printStackTrace();
-                log.error(e.getMessage());
-                throw new QSException(e.getMessage());
+                log.error("Failed to execute request action", e);
+                String message =
+                        e.getMessage() != null ? e.getMessage() : e.getClass().getSimpleName();
+                throw new QSException(message, e);
             }
         }
     }
@@ -105,7 +106,7 @@ public void onResponse(Call call, Response response) {
                                 callBack.onAPIResponse(m);
                             }
                         } catch (Exception e) {
-                            log.error(e.getMessage());
+                            log.error("Failed to parse response", e);
                             onOkhttpFailure(e, callBack, outputClass);
                         } finally {
                             response.close();
@@ -124,11 +125,13 @@ private <T extends OutputModel> void onOkhttpFailure(
                 if (e instanceof CancellationHandler.CancellationException)
                     errorCode = QSConstant.REQUEST_ERROR_CANCELLED; // Cancelled by users.
                 T m = QSParamInvokeUtil.getOutputModel(outputClass);
-                fillResponseCallbackModel(errorCode, e.getMessage(), m);
+                String message =
+                        e.getMessage() != null ? e.getMessage() : e.getClass().getSimpleName();
+                fillResponseCallbackModel(errorCode, message, m);
                 callBack.onAPIResponse(m);
             }
         } catch (Exception ex) {
-            log.error(ex.getMessage());
+            log.error("Failed in onOkhttpFailure", ex);
         }
     }
 
diff --git a/src/test/java/com/qingstor/sdk/exception/QSExceptionTest.java b/src/test/java/com/qingstor/sdk/exception/QSExceptionTest.java
new file mode 100644
index 00000000..633754d4
--- /dev/null
+++ b/src/test/java/com/qingstor/sdk/exception/QSExceptionTest.java
@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2021 Yunify, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this work except in compliance with the License.
+ * You may obtain a copy of the License in the LICENSE file, or at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.qingstor.sdk.exception;
+
+import java.io.EOFException;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class QSExceptionTest {
+
+    @Test
+    public void testMessageWithMessageOnly() {
+        QSException e = new QSException("test error");
+        Assert.assertEquals("Error Code: 0; Error Message: test error", e.getMessage());
+    }
+
+    @Test
+    public void testMessageWithMessageAndCause() {
+        Exception cause = new Exception("cause error");
+        QSException e = new QSException("wrapper error", cause);
+        Assert.assertEquals(
+                "Error Code: 0; Error Message: wrapper error\ncause error", e.getMessage());
+    }
+
+    @Test
+    public void testMessageWithCauseHavingNullMessage() {
+        EOFException cause = new EOFException();
+        QSException e = new QSException("EOFException", cause);
+        Assert.assertEquals("Error Code: 0; Error Message: EOFException", e.getMessage());
+    }
+
+    @Test
+    public void testMessageWithNullMessageAndCause() {
+        EOFException cause = new EOFException();
+        QSException e = new QSException(null, cause);
+        Assert.assertEquals("Error Code: 0; Error Message: java.io.EOFException", e.getMessage());
+    }
+
+    @Test
+    public void testMessageWithThrowableConstructor() {
+        NullPointerException cause = new NullPointerException();
+        QSException e = new QSException(cause);
+        Assert.assertEquals(
+                "Error Code: 0; Error Message: java.lang.NullPointerException", e.getMessage());
+    }
+
+    @Test
+    public void testMessageWithNullMessageAndNullCause() {
+        QSException e = new QSException((String) null);
+        Assert.assertEquals("Error Code: 0; Error Message: Unknown", e.getMessage());
+    }
+}