diff --git a/.github/workflows/run_test.yaml b/.github/workflows/run_test.yaml
index 6757ae2d..71cc8c10 100644
--- a/.github/workflows/run_test.yaml
+++ b/.github/workflows/run_test.yaml
@@ -4,7 +4,7 @@ on:
   push:
     branches: [ master ]
   pull_request:
-    branches: [ master ]
+    branches: [ master, 'v*' ]
   schedule:
     - cron: '0 6 * * *'
 
diff --git a/nebula2/gclient/net/ConnectionPool.py b/nebula2/gclient/net/ConnectionPool.py
index 07fc549b..9379eb0c 100644
--- a/nebula2/gclient/net/ConnectionPool.py
+++ b/nebula2/gclient/net/ConnectionPool.py
@@ -149,6 +149,7 @@ def get_connection(self):
             try:
                 ok_num = self.get_ok_servers_num()
                 if ok_num == 0:
+                    logging.error('No available server')
                     return None
                 max_con_per_address = int(self._configs.max_connection_pool_size / ok_num)
                 try_count = 0
@@ -162,15 +163,13 @@ def get_connection(self):
                                     connection.is_used = True
                                     logging.info('Get connection to {}'.format(addr))
                                     return connection
+                                # remove unusable connection
+                                self._connections[addr].remove(connection)
 
                         if len(self._connections[addr]) < max_con_per_address:
                             connection = Connection()
-                            if self._ssl_configs is None:
-                                connection.open(
-                                    addr[0], addr[1], self._configs.timeout)
-                            else:
-                                connection.open_SSL(
-                                    addr[0], addr[1], self._configs.timeout, self._ssl_configs)
+                            connection.open_SSL(
+                                addr[0], addr[1], self._configs.timeout, self._ssl_configs)
                             connection.is_used = True
                             self._connections[addr].append(connection)
                             logging.info('Get connection to {}'.format(addr))
diff --git a/tests/test_pool.py b/tests/test_pool.py
index 9a15352b..a45ed701 100644
--- a/tests/test_pool.py
+++ b/tests/test_pool.py
@@ -42,7 +42,7 @@ def setup_class(self):
         self.configs.interval_check = 2
         self.pool = ConnectionPool()
         assert self.pool.init(self.addresses, self.configs)
-        assert self.pool.connnects() == 2
+        assert self.pool.connects() == 2
 
     def test_right_hostname(self):
         pool = ConnectionPool()
@@ -108,7 +108,7 @@ def test_get_session(self):
             session.release()
 
         assert self.pool.in_used_connects() == 0
-        assert self.pool.connnects() == 4
+        assert self.pool.connects() == 4
 
         # test get session after release
         for num in range(0, self.configs.max_connection_pool_size - 1):
@@ -118,10 +118,10 @@ def test_get_session(self):
             sessions.append(session)
 
         assert self.pool.in_used_connects() == 3
-        assert self.pool.connnects() == 4
+        assert self.pool.connects() == 4
         # test the idle connection delete
         time.sleep(5)
-        assert self.pool.connnects() == 3
+        assert self.pool.connects() == 3
 
     def test_stop_close(self):
         session = self.pool.get_session('root', 'nebula')
diff --git a/tests/test_session.py b/tests/test_session.py
index cded39ca..6796f08b 100644
--- a/tests/test_session.py
+++ b/tests/test_session.py
@@ -31,7 +31,7 @@ def setup_class(self):
                                ('127.0.0.1', 9670),
                                ('127.0.0.1', 9671)],
                               self.configs)
-        assert self.pool.connnects() == 0
+        assert self.pool.connects() == 0
         assert self.pool.in_used_connects() == 0
 
     def test_1_release_by_del(self):