diff --git a/.travis.yml b/.travis.yml
index 6044fd53..92611011 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,6 @@
 sudo: false
 language: python
 python:
-- '2.6'
 - '2.7'
 - '3.5'
 - '3.6'
diff --git a/qcloud_cos/cos_client.py b/qcloud_cos/cos_client.py
index a56a27bb..f2658111 100644
--- a/qcloud_cos/cos_client.py
+++ b/qcloud_cos/cos_client.py
@@ -209,8 +209,8 @@ def send_request(self, method, url, bucket, timeout=30, **kwargs):
         kwargs['headers'] = format_values(kwargs['headers'])
         if 'data' in kwargs:
             kwargs['data'] = to_bytes(kwargs['data'])
-        try:
-            for j in range(self._retry):
+        for j in range(self._retry + 1):
+            try:
                 if method == 'POST':
                     res = self._session.post(url, timeout=timeout, **kwargs)
                 elif method == 'GET':
@@ -223,9 +223,11 @@ def send_request(self, method, url, bucket, timeout=30, **kwargs):
                     res = self._session.head(url, timeout=timeout, **kwargs)
                 if res.status_code < 400:  # 2xx和3xx都认为是成功的
                     return res
-        except Exception as e:  # 捕获requests抛出的如timeout等客户端错误,转化为客户端错误
-            logger.exception('url:%s, exception:%s' % (url, str(e)))
-            raise CosClientError(str(e))
+            except Exception as e:  # 捕获requests抛出的如timeout等客户端错误,转化为客户端错误
+                logger.exception('url:%s, retry_time:%d exception:%s' % (url, j, str(e)))
+                if j < self._retry:
+                    continue
+                raise CosClientError(str(e))
 
         if res.status_code >= 400:  # 所有的4XX,5XX都认为是COSServiceError
             if method == 'HEAD' and res.status_code == 404:   # Head 需要处理
diff --git a/qcloud_cos/version.py b/qcloud_cos/version.py
index 3ba8b1cf..72954835 100644
--- a/qcloud_cos/version.py
+++ b/qcloud_cos/version.py
@@ -1,2 +1,2 @@
 
-__version__ = '5.1.7.1'
+__version__ = '5.1.7.2'
diff --git a/ut/test.py b/ut/test.py
index fb98f7ef..32cc1c2b 100644
--- a/ut/test.py
+++ b/ut/test.py
@@ -24,7 +24,7 @@
     SecretId=SECRET_ID,
     SecretKey=SECRET_KEY,
 )
-client = CosS3Client(conf)
+client = CosS3Client(conf, retry=3)
 
 
 def _create_test_bucket(test_bucket):
@@ -638,6 +638,18 @@ def test_list_multipart_uploads():
         )
 
 
+def test_upload_file_from_buffer():
+    import io
+    data = io.BytesIO(6*1024*1024*b'A')
+    response = client.upload_file_from_buffer(
+        Bucket=test_bucket,
+        Key='test_upload_from_buffer',
+        Body=data,
+        MaxBufferSize=5,
+        PartSize=1
+    )
+
+
 def test_upload_file_multithreading():
     """根据文件大小自动选择分块大小,多线程并发上传提高上传速度"""
     file_name = "thread_1GB"
@@ -650,7 +662,7 @@ def test_upload_file_multithreading():
         Bucket=test_bucket,
         Key=file_name,
         LocalFilePath=file_name,
-        MAXThread=10,
+        MAXThread=5,
         EnableMD5=True
     )
     ed = time.time()  # 记录结束时间