diff --git a/chat_stream_test.go b/chat_stream_test.go
index 77d373c..19c2e3c 100644
--- a/chat_stream_test.go
+++ b/chat_stream_test.go
@@ -255,6 +255,67 @@ func TestCreateChatCompletionStreamRateLimitError(t *testing.T) {
 	t.Logf("%+v\n", apiErr)
 }
 
+func TestAzureCreateChatCompletionStreamRateLimitError(t *testing.T) {
+	wantCode := "429"
+	wantMessage := "Requests to the Creates a completion for the chat message Operation under Azure OpenAI API " +
+		"version 2023-03-15-preview have exceeded token rate limit of your current OpenAI S0 pricing tier. " +
+		"Please retry after 20 seconds. " +
+		"Please go here: https://aka.ms/oai/quotaincrease if you would like to further increase the default rate limit."
+
+	server := test.NewTestServer()
+	server.RegisterHandler("/openai/deployments/gpt-35-turbo/chat/completions",
+		func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.WriteHeader(http.StatusTooManyRequests)
+			// Send test responses
+			dataBytes := []byte(`{"error": { "code": "` + wantCode + `", "message": "` + wantMessage + `"}}`)
+			_, err := w.Write(dataBytes)
+
+			checks.NoError(t, err, "Write error")
+		})
+	// create the test server
+	var err error
+	ts := server.OpenAITestServer()
+	ts.Start()
+	defer ts.Close()
+
+	config := DefaultAzureConfig(test.GetTestToken(), ts.URL)
+	client := NewClientWithConfig(config)
+	ctx := context.Background()
+
+	request := ChatCompletionRequest{
+		MaxTokens: 5,
+		Model:     GPT3Dot5Turbo,
+		Messages: []ChatCompletionMessage{
+			{
+				Role:    ChatMessageRoleUser,
+				Content: "Hello!",
+			},
+		},
+		Stream: true,
+	}
+
+	apiErr := &APIError{}
+	_, err = client.CreateChatCompletionStream(ctx, request)
+	if !errors.As(err, &apiErr) {
+		t.Errorf("Did not return APIError: %+v\n", apiErr)
+		return
+	}
+	if apiErr.HTTPStatusCode != http.StatusTooManyRequests {
+		t.Errorf("Did not return HTTPStatusCode got = %d, want = %d\n", apiErr.HTTPStatusCode, http.StatusTooManyRequests)
+		return
+	}
+	code, ok := apiErr.Code.(string)
+	if !ok || code != wantCode {
+		t.Errorf("Did not return Code. got = %v, want = %s\n", apiErr.Code, wantCode)
+		return
+	}
+	if apiErr.Message != wantMessage {
+		t.Errorf("Did not return Message. got = %s, want = %s\n", apiErr.Message, wantMessage)
+		return
+	}
+}
+
 func TestCreateChatCompletionStreamErrorAccumulatorWriteErrors(t *testing.T) {
 	var err error
 	server := test.NewTestServer()
diff --git a/client_test.go b/client_test.go
index 5e63539..c96ceb7 100644
--- a/client_test.go
+++ b/client_test.go
@@ -134,6 +134,15 @@ func TestHandleErrorResp(t *testing.T) {
 				}`)),
 			expected: "error, status code: 503, message: That model...",
 		},
+		{
+			name:     "503 no message (Unknown response)",
+			httpCode: http.StatusServiceUnavailable,
+			body: bytes.NewReader([]byte(`
+				{
+					"error":{}
+				}`)),
+			expected: "error, status code: 503, message: ",
+		},
 	}
 
 	for _, tc := range testCases {
diff --git a/error.go b/error.go
index 6354f43..b789ed7 100644
--- a/error.go
+++ b/error.go
@@ -44,9 +44,13 @@ func (e *APIError) UnmarshalJSON(data []byte) (err error) {
 		return
 	}
 
-	err = json.Unmarshal(rawMap["type"], &e.Type)
-	if err != nil {
-		return
+	// optional fields for azure openai
+	// refs: https://github.com/sashabaranov/go-openai/issues/343
+	if _, ok := rawMap["type"]; ok {
+		err = json.Unmarshal(rawMap["type"], &e.Type)
+		if err != nil {
+			return
+		}
 	}
 
 	// optional fields