diff --git a/serializer/serializer.c b/serializer/serializer.c
index 562a1935..338d5b9c 100644
--- a/serializer/serializer.c
+++ b/serializer/serializer.c
@@ -260,7 +260,7 @@ status_t ta_send_transfer_req_deserialize(const char* const obj,
   }
 
   json_result = cJSON_GetObjectItemCaseSensitive(json_obj, "tag");
-  if (json_result != NULL) {
+  if (json_result != NULL && json_result->valuestring != NULL) {
     tag_len = strnlen(json_result->valuestring, NUM_TRYTES_TAG);
 
     // If 'tag' is less than 27 trytes (NUM_TRYTES_TAG), expands it
@@ -297,7 +297,7 @@ status_t ta_send_transfer_req_deserialize(const char* const obj,
   }
 
   json_result = cJSON_GetObjectItemCaseSensitive(json_obj, "message");
-  if (json_result != NULL) {
+  if (json_result != NULL && json_result->valuestring != NULL) {
     if (raw_message) {
       msg_len = strlen(json_result->valuestring) * 2;
       req->msg_len = msg_len * 3;
@@ -322,7 +322,8 @@ status_t ta_send_transfer_req_deserialize(const char* const obj,
   }
 
   json_result = cJSON_GetObjectItemCaseSensitive(json_obj, "address");
-  if (json_result != NULL && (strnlen(json_result->valuestring, 81) == 81)) {
+  if (json_result != NULL && json_result->valuestring != NULL &&
+      (strnlen(json_result->valuestring, 81) == 81)) {
     flex_trits_from_trytes(address_trits, NUM_TRITS_HASH,
                            (const tryte_t*)json_result->valuestring,
                            NUM_TRYTES_HASH, NUM_TRYTES_HASH);
diff --git a/tests/regression/1_close_TA.sh b/tests/regression/1_close_TA.sh
index 230128f4..84ba585c 100644
--- a/tests/regression/1_close_TA.sh
+++ b/tests/regression/1_close_TA.sh
@@ -1,8 +1,8 @@
 #!/usr/bin/env bash
 
 wait $(ps aux | grep '[r]unner.py' | awk '{print $2}')
-kill $(ps aux | grep '[.]/accelerator' | awk '{print $2}')
-wait $!
+wait $(kill $(ps aux | grep '[r]edis' | awk '{print $2}'))
+wait $(kill $(ps aux | grep '[.]/accelerator' | awk '{print $2}'))
 
 trap 'exit 0' SIGTERM
 
diff --git a/tests/regression/1_run_TA.sh b/tests/regression/1_run_TA.sh
index fa2a63f9..18de721d 100644
--- a/tests/regression/1_run_TA.sh
+++ b/tests/regression/1_run_TA.sh
@@ -1,8 +1,10 @@
 make
 
+redis-server &
+
 bazel run //accelerator &
 TA_pid=$!
-sleep 20
+sleep 5
 
 pip install --user -r tests/regression/requirements.txt
 
diff --git a/tests/regression/runner.py b/tests/regression/runner.py
index 372721ba..c2104be0 100644
--- a/tests/regression/runner.py
+++ b/tests/regression/runner.py
@@ -14,7 +14,7 @@
     raw_url = sys.argv[1]
 elif len(sys.argv) == 3:
     raw_url = sys.argv[1]
-    # if DEBUG_FLAG field == `Y`, then starts debugging mode
+    # if DEBUG_FLAG field == `Y`, then starts debugging mode with less iteration in statistical tests
     if sys.argv[2] == 'y' or sys.argv[2] == 'Y':
         DEBUG_FLAG = True
 else:
@@ -27,13 +27,14 @@
 MSG_STATUS_CODE_405 = "[405] Method Not Allowed"
 MSG_STATUS_CODE_400 = "{\"message\":\"Invalid request header\"}"
 MSG_STATUS_CODE_404 = "404 Not Found"
+MSG_STATUS_CODE_500 = "500"
 EMPTY_REPLY = "000"
 LEN_TAG = 27
 LEN_ADDR = 81
 LEN_MSG_SIGN = 2187
 tryte_alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ9"
 
-if DEBUG_FLAG == True:
+if sys.argv[2] == 'Y':
     TIMES_TOTAL = 2
 else:
     TIMES_TOTAL = 100
@@ -97,7 +98,7 @@ def API(get_query, get_data=None, post_data=None, delay=True):
         return None
     if not response:
         response = ""
-    
+
     if delay == True:
         time.sleep(2)
     return response
@@ -122,7 +123,7 @@ def test_mam_send_msg(self):
             "JSON msg with wrong key"
         ]
 
-        pass_case = [0, 1]
+        pass_case = [0, 1, 4]
         for i in range(len(test_cases)):
             if i not in pass_case:
                 test_cases[i].encode(encoding='utf-8')
@@ -155,7 +156,8 @@ def test_mam_send_msg(self):
                                              LEN_ADDR))
             else:
                 self.assertTrue(EMPTY_REPLY in response[i]
-                                or MSG_STATUS_CODE_404 in response[i])
+                                or MSG_STATUS_CODE_404 in response[i]
+                                or MSG_STATUS_CODE_500 in response[i])
 
         # Time Statistics
         payload = "Who are we? Just a speck of dust within the galaxy?"
@@ -266,7 +268,7 @@ def test_send_transfer(self):
                 logging.debug("send transfer i = " + str(i) + ", response = " +
                               response[i])
 
-        pass_case = [0, 1, 2]
+        pass_case = [0, 1, 2, 3]
         for i in range(len(response)):
             logging.debug("send transfer i = " + str(i) + ", response = " +
                           response[i])
@@ -291,7 +293,8 @@ def test_send_transfer(self):
                                  LEN_MSG_SIGN))
             else:
                 self.assertTrue(EMPTY_REPLY in response[i]
-                                or MSG_STATUS_CODE_404 in response[i])
+                                or MSG_STATUS_CODE_404 in response[i]
+                                or MSG_STATUS_CODE_500 in response[i])
 
         # Time Statistics
         time_cost = []
@@ -333,5 +336,5 @@ def test_send_transfer(self):
         logging.basicConfig(level=logging.INFO)
     unittest.main(argv=['first-arg-is-ignored'], exit=False)
 
-    if not unittest.TestResult().errors:
+    if len(unittest.TestResult().errors) != 0:
         exit(1)