diff --git a/lib/ga4.py b/lib/ga4.py
index 26b8289..bd9ad37 100644
--- a/lib/ga4.py
+++ b/lib/ga4.py
@@ -4,6 +4,7 @@ sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))
 import yaml
 import pprint
 from datetime import datetime, timedelta
+from dateutil.parser import parse
 from google.analytics.data import BetaAnalyticsDataClient
 from google.analytics.data_v1beta.types import DateRange, Dimension, Metric, RunReportRequest
 from sqlalchemy.dialects.mysql import insert as mysql_insert
@@ -74,6 +75,7 @@ def detect_max_rows_supported(client, property_id):
 # GA4 데이터 요청
 # ------------------------
 def fetch_report(client, property_id, start_date, end_date, dimensions, metrics, limit=10000):
+    print(f"[INFO] fetch_report 호출 - 기간: {start_date} ~ {end_date}, dims={dimensions}, metrics={metrics}")
     request = RunReportRequest(
         property=f"properties/{property_id}",
         dimensions=[Dimension(name=d) for d in dimensions],
@@ -82,7 +84,7 @@ def fetch_report(client, property_id, start_date, end_date, dimensions, metrics,
         limit=limit,
     )
     response = client.run_report(request)
-    print(f"[INFO] GA4 리포트 응답 받음: {len(response.rows)} rows - dims={dimensions}, metrics={metrics}")
+    print(f"[INFO] GA4 리포트 응답 받음: {len(response.rows)} rows")
     return response
 
 # ------------------------
@@ -95,21 +97,22 @@ def save_report_to_db(engine, table, response, dimension_names, metric_names, de
             mets = row.metric_values
             data = {}
             for i, dim_name in enumerate(dimension_names):
-                val = dims[i].value
-                if dim_name == "date":
-                    if len(val) == 8:
-                        val = datetime.strptime(val, "%Y%m%d").date()
-                    else:
-                        try:
-                            val = datetime.strptime(val, "%Y-%m-%d").date()
-                        except:
-                            pass
-                data[dim_name] = val
+                try:
+                    val = dims[i].value
+                    if dim_name == "date":
+                        if len(val) == 8:
+                            val = datetime.strptime(val, "%Y%m%d").date()
+                        else:
+                            val = parse(val).date()
+                    data[dim_name] = val
+                except IndexError:
+                    print(f"[WARNING] dimension index {i} 초과: dims={dims}")
 
             for i, met_name in enumerate(metric_names):
                 try:
                     data[met_name] = int(mets[i].value)
-                except:
+                except (IndexError, ValueError):
+                    print(f"[WARNING] metric 처리 오류: {met_name}")
                     data[met_name] = None
 
             stmt = mysql_insert(table).values(**data)
@@ -136,6 +139,7 @@ def get_latest_date_from_db(engine, table):
     with engine.connect() as conn:
         stmt = select(func.max(table.c.date))
         result = conn.execute(stmt).scalar()
+        print(f"[INFO] DB 기준 마지막 저장 날짜: {result}")
         return result
 
 # ------------------------
@@ -165,21 +169,25 @@ def determine_date_range(table, config_start, config_end, force_update, engine):
         else:
             actual_start = config_start
 
+    # 시작일이 종료일보다 뒤에 있으면 자동 교체
     if actual_start > actual_end:
-        return None, None
+        print(f"[WARN] 시작일({actual_start})이 종료일({actual_end})보다 뒤에 있습니다. 날짜를 교환하여 수집을 계속합니다.")
+        actual_start, actual_end = actual_end, actual_start
 
+    print(f"[INFO] 수집 날짜 범위 결정: {actual_start} ~ {actual_end}")
     return actual_start, actual_end
 
+
 # ------------------------
 # 단일 테이블 단위 데이터 처리
 # ------------------------
 def process_dimension_metric(engine, client, property_id, config, table, dims, mets, max_rows, debug=False, force_update=False):
-    config_start = datetime.strptime(config.get("startDt", "20230101"), "%Y%m%d").date()
-    config_end = datetime.strptime(config.get("endDt", datetime.now().strftime("%Y%m%d")), "%Y%m%d").date()
+    config_start = parse(config.get("startDt", "2023-01-01")).date()
+    config_end = parse(config.get("endDt", datetime.now().strftime("%Y-%m-%d")).strip()).date()
     actual_start, actual_end = determine_date_range(table, config_start, config_end, force_update, engine)
 
     if actual_start is None or actual_end is None:
-        print(f"[INFO] 이미 모든 데이터가 수집되어 있습니다 또는 수집 범위가 없습니다.")
+        print(f"[INFO] 모든 데이터가 이미 수집되었거나 수집 범위가 없습니다.")
         return
 
     for start_dt, end_dt in date_range_chunks(actual_start, actual_end, max_rows):
@@ -196,6 +204,7 @@ def process_dimension_metric(engine, client, property_id, config, table, dims, m
 # 메인 진입점 (병렬 처리 포함)
 # ------------------------
 def main():
+    print("[INFO] GA4 수집 프로그램 시작")
     config = load_config()
     ga4_cfg = config.get('ga4', {})
     service_account_file = ga4_cfg.get('service_account_file')
@@ -215,6 +224,7 @@ def main():
     if not max_rows:
         max_rows = detect_max_rows_supported(client, property_id)
         update_config_file_with_max_rows(max_rows)
+    print(f"[INFO] 설정된 max_rows_per_request = {max_rows}")
 
     tasks = [
         (db_schema.ga4_by_date,     ["date"], ["activeUsers", "screenPageViews", "sessions"]),
@@ -231,8 +241,12 @@ def main():
                             table, dims, mets, max_rows, debug, force_update)
             for table, dims, mets in tasks
         ]
-        for future in as_completed(futures):
-            future.result()
+        for i, future in enumerate(as_completed(futures)):
+            try:
+                future.result()
+                print(f"[INFO] 태스크 {i} 완료")
+            except Exception as e:
+                print(f"[ERROR] 태스크 {i} 실패: {e}")
 
     print("[INFO] GA4 데이터 수집 및 저장 완료")