diff --git a/server/api_server/sessions_endpoint.py b/server/api_server/sessions_endpoint.py
index 113a8250..147dbbe3 100755
--- a/server/api_server/sessions_endpoint.py
+++ b/server/api_server/sessions_endpoint.py
@@ -208,6 +208,7 @@ def get_device_sessions(mac, period):
     cur.execute(sql, (mac,))
     rows = cur.fetchall()
     conn.close()
+    tz_name = get_setting_value("TIMEZONE") or "UTC"
 
     table_data = {"data": []}
 
@@ -230,9 +231,9 @@ def get_device_sessions(mac, period):
         if row["ses_EventTypeConnection"] in ("<missing event>", None) or row["ses_EventTypeDisconnection"] in ("<missing event>", None):
             dur = "..."
         elif row["ses_StillConnected"]:
-            dur = format_date_diff(row["ses_DateTimeConnection"], None)["text"]
+            dur = format_date_diff(row["ses_DateTimeConnection"], None, tz_name)["text"]
         else:
-            dur = format_date_diff(row["ses_DateTimeConnection"], row["ses_DateTimeDisconnection"])["text"]
+            dur = format_date_diff(row["ses_DateTimeConnection"], row["ses_DateTimeDisconnection"], tz_name)["text"]
 
         # Additional Info
         info = row["ses_AdditionalInfo"]
@@ -350,11 +351,11 @@ def get_session_events(event_type, period_date):
         if event_type in ("sessions", "missing"):
             # Duration
             if row[5] and row[6]:
-                delta = format_date_diff(row[5], row[6])
+                delta = format_date_diff(row[5], row[6], tz_name)
                 row[7] = delta["text"]
                 row[8] = int(delta["total_minutes"] * 60)  # seconds
             elif row[12] == 1:
-                delta = format_date_diff(row[5], None)
+                delta = format_date_diff(row[5], None, tz_name)
                 row[7] = delta["text"]
                 row[8] = int(delta["total_minutes"] * 60)  # seconds
             else:
diff --git a/server/utils/datetime_utils.py b/server/utils/datetime_utils.py
index b8f7d1dc..a74234b4 100644
--- a/server/utils/datetime_utils.py
+++ b/server/utils/datetime_utils.py
@@ -4,19 +4,17 @@ import os
 import pathlib
 import sys
 from datetime import datetime
+import datetime
 import pytz
 from pytz import timezone
-import datetime
 from typing import Union
+from zoneinfo import ZoneInfo
+import email.utils
 
 # Register NetAlertX directories
 INSTALL_PATH="/app"
 sys.path.extend([f"{INSTALL_PATH}/front/plugins", f"{INSTALL_PATH}/server"])
 
-
-# Register NetAlertX directories
-INSTALL_PATH="/app"
-
 import conf
 from const import *
 
@@ -115,17 +113,16 @@ def format_date(date_str: str) -> str:
             now = datetime.datetime.now(conf.tz)
             dt = dt.replace(tzinfo=now.astimezone().tzinfo)
         return dt.astimezone().isoformat()
-    except Exception:
+    except (ValueError, AttributeError, TypeError):
         return "invalid"
 
-def format_date_diff(date1, date2):
+def format_date_diff(date1, date2, tz_name):
     """
     Return difference between two datetimes as 'Xd   HH:MM'.
     Uses app timezone if datetime is naive.
     date2 can be None (uses now).
     """
-    # Get timezone from settings
-    tz_name = get_setting_value("TIMEZONE") or "UTC"
+    # Get timezone from settings    
     tz = pytz.timezone(tz_name)
 
     def parse_dt(dt):
@@ -134,9 +131,9 @@ def format_date_diff(date1, date2):
         if isinstance(dt, str):
             try:
                 dt_parsed = email.utils.parsedate_to_datetime(dt)
-            except Exception:
-                # fallback: parse ISO string
-                dt_parsed = datetime.datetime.fromisoformat(dt)
+            except (ValueError, TypeError):
+             # fallback: parse ISO string
+             dt_parsed = datetime.datetime.fromisoformat(dt)
             # convert naive GMT/UTC to app timezone
             if dt_parsed.tzinfo is None:
                 dt_parsed = tz.localize(dt_parsed)