diff --git a/__test__/components/Menubar.test.tsx b/__test__/components/Menubar.test.tsx
index 896d43e..55a5d6c 100644
--- a/__test__/components/Menubar.test.tsx
+++ b/__test__/components/Menubar.test.tsx
@@ -55,6 +55,139 @@ describe("Calendar App Component Display Tests", () => {
     expect(screen.getByText("t")).toBeInTheDocument();
   });
 
+  // Edge cases for avatar display logic
+  it("handles user with only family_name", () => {
+    (window as any).appList = [{ name: "test", icon: "test", link: "test" }];
+    const preloadedState = {
+      user: {
+        userData: {
+          sub: "test",
+          email: "test@test.com",
+          family_name: "Smith",
+          name: null,
+          sid: "mockSid",
+          openpaasId: "667037022b752d0026472254",
+        },
+      },
+    };
+    renderWithProviders(<Menubar />, preloadedState);
+    expect(screen.getByText("t")).toBeInTheDocument();
+  });
+
+  it("handles user with only name", () => {
+    (window as any).appList = [{ name: "test", icon: "test", link: "test" }];
+    const preloadedState = {
+      user: {
+        userData: {
+          sub: "test",
+          email: "test@test.com",
+          family_name: null,
+          name: "John",
+          sid: "mockSid",
+          openpaasId: "667037022b752d0026472254",
+        },
+      },
+    };
+    renderWithProviders(<Menubar />, preloadedState);
+    expect(screen.getByText("t")).toBeInTheDocument();
+  });
+
+  it("handles user with both name and family_name", () => {
+    (window as any).appList = [{ name: "test", icon: "test", link: "test" }];
+    const preloadedState = {
+      user: {
+        userData: {
+          sub: "test",
+          email: "test@test.com",
+          family_name: "Doe",
+          name: "John",
+          sid: "mockSid",
+          openpaasId: "667037022b752d0026472254",
+        },
+      },
+    };
+    renderWithProviders(<Menubar />, preloadedState);
+    expect(screen.getByText("JD")).toBeInTheDocument();
+  });
+
+  it("handles user with no name and family_name", () => {
+    (window as any).appList = [{ name: "test", icon: "test", link: "test" }];
+    const preloadedState = {
+      user: {
+        userData: {
+          sub: "test",
+          email: "test@test.com",
+          family_name: null,
+          name: null,
+          sid: "mockSid",
+          openpaasId: "667037022b752d0026472254",
+        },
+      },
+    };
+    renderWithProviders(<Menubar />, preloadedState);
+    expect(screen.getByText("t")).toBeInTheDocument();
+  });
+
+  it("handles user with empty email", () => {
+    (window as any).appList = [{ name: "test", icon: "test", link: "test" }];
+    const preloadedState = {
+      user: {
+        userData: {
+          sub: "test",
+          email: "",
+          family_name: null,
+          name: null,
+          sid: "mockSid",
+          openpaasId: "667037022b752d0026472254",
+        },
+      },
+    };
+    renderWithProviders(<Menubar />, preloadedState);
+    // Should not crash and show empty string
+    const avatar = screen.getByRole("img", { hidden: true });
+    expect(avatar).toBeInTheDocument();
+  });
+
+  it("handles user with null email", () => {
+    (window as any).appList = [{ name: "test", icon: "test", link: "test" }];
+    const preloadedState = {
+      user: {
+        userData: {
+          sub: "test",
+          email: null,
+          family_name: null,
+          name: null,
+          sid: "mockSid",
+          openpaasId: "667037022b752d0026472254",
+        },
+      },
+    };
+    renderWithProviders(<Menubar />, preloadedState);
+    // Should not crash and show empty string
+    const avatar = screen.getByRole("img", { hidden: true });
+    expect(avatar).toBeInTheDocument();
+  });
+
+  it("handles user with undefined email", () => {
+    (window as any).appList = [{ name: "test", icon: "test", link: "test" }];
+    const preloadedState = {
+      user: {
+        userData: {
+          sub: "test",
+          email: undefined,
+          family_name: null,
+          name: null,
+          sid: "mockSid",
+          openpaasId: "667037022b752d0026472254",
+        },
+      },
+    };
+    renderWithProviders(<Menubar />, preloadedState);
+    // Should not crash and show empty string
+    const avatar = screen.getByRole("img", { hidden: true });
+    expect(avatar).toBeInTheDocument();
+  });
+
   it("shows AppsIcon when applist is not empty", () => {
     (window as any).appList = [{ name: "test", icon: "test", link: "test" }];
     renderWithProviders(<Menubar />, preloadedState);
diff --git a/__test__/features/Events/eventUtils.test.ts b/__test__/features/Events/eventUtils.test.ts
index 4cb01b1..fca445f 100644
--- a/__test__/features/Events/eventUtils.test.ts
+++ b/__test__/features/Events/eventUtils.test.ts
@@ -465,4 +465,202 @@ describe("calendarEventToJCal", () => {
       ])
     );
   });
+
+  // Edge cases for timezone fallback
+  it("handles invalid timezone with UTC fallback", () => {
+    const mockEvent = {
+      uid: "event-invalid-tz",
+      title: "Invalid Timezone Event",
+      start: new Date("2025-07-23T10:00:00"),
+      end: new Date("2025-07-23T11:00:00"),
+      timezone: "Invalid/Timezone",
+      allday: false,
+      attendee: [],
+    };
+
+    const result = calendarEventToJCal(mockEvent as CalendarEvent);
+
+    expect(result[0]).toBe("vcalendar");
+    const [vevent, vtimezone] = result[2];
+    expect(vevent[0]).toBe("vevent");
+    expect(vtimezone[0]).toBe("vtimezone");
+
+    // Should use UTC timezone as fallback - check for UTC standard timezone
+    expect(vtimezone[2]).toEqual(
+      expect.arrayContaining([
+        [
+          "standard",
+          [
+            ["tzoffsetfrom", {}, "utc-offset", "+00:00"],
+            ["tzoffsetto", {}, "utc-offset", "+00:00"],
+            ["tzname", {}, "text", "UTC"],
+            ["dtstart", {}, "date-time", "1970-01-01T00:00:00"],
+          ],
+          [],
+        ],
+      ])
+    );
+  });
+
+  it("handles null timezone with UTC fallback", () => {
+    const mockEvent = {
+      uid: "event-null-tz",
+      title: "Null Timezone Event",
+      start: new Date("2025-07-23T10:00:00"),
+      end: new Date("2025-07-23T11:00:00"),
+      timezone: null,
+      allday: false,
+      attendee: [],
+    };
+
+    const result = calendarEventToJCal(mockEvent as CalendarEvent);
+
+    expect(result[0]).toBe("vcalendar");
+    const [vevent, vtimezone] = result[2];
+    expect(vevent[0]).toBe("vevent");
+    expect(vtimezone[0]).toBe("vtimezone");
+
+    // Should use UTC timezone as fallback
+    expect(vtimezone[2]).toEqual(
+      expect.arrayContaining([
+        [
+          "standard",
+          [
+            ["tzoffsetfrom", {}, "utc-offset", "+00:00"],
+            ["tzoffsetto", {}, "utc-offset", "+00:00"],
+            ["tzname", {}, "text", "UTC"],
+            ["dtstart", {}, "date-time", "1970-01-01T00:00:00"],
+          ],
+          [],
+        ],
+      ])
+    );
+  });
+
+  it("handles undefined timezone with UTC fallback", () => {
+    const mockEvent = {
+      uid: "event-undefined-tz",
+      title: "Undefined Timezone Event",
+      start: new Date("2025-07-23T10:00:00"),
+      end: new Date("2025-07-23T11:00:00"),
+      timezone: undefined,
+      allday: false,
+      attendee: [],
+    };
+
+    const result = calendarEventToJCal(mockEvent as CalendarEvent);
+
+    expect(result[0]).toBe("vcalendar");
+    const [vevent, vtimezone] = result[2];
+    expect(vevent[0]).toBe("vevent");
+    expect(vtimezone[0]).toBe("vtimezone");
+
+    // Should use UTC timezone as fallback
+    expect(vtimezone[2]).toEqual(
+      expect.arrayContaining([
+        [
+          "standard",
+          [
+            ["tzoffsetfrom", {}, "utc-offset", "+00:00"],
+            ["tzoffsetto", {}, "utc-offset", "+00:00"],
+            ["tzname", {}, "text", "UTC"],
+            ["dtstart", {}, "date-time", "1970-01-01T00:00:00"],
+          ],
+          [],
+        ],
+      ])
+    );
+  });
+
+  it("handles empty string timezone with UTC fallback", () => {
+    const mockEvent = {
+      uid: "event-empty-tz",
+      title: "Empty Timezone Event",
+      start: new Date("2025-07-23T10:00:00"),
+      end: new Date("2025-07-23T11:00:00"),
+      timezone: "",
+      allday: false,
+      attendee: [],
+    };
+
+    const result = calendarEventToJCal(mockEvent as CalendarEvent);
+
+    expect(result[0]).toBe("vcalendar");
+    const [vevent, vtimezone] = result[2];
+    expect(vevent[0]).toBe("vevent");
+    expect(vtimezone[0]).toBe("vtimezone");
+
+    // Should use UTC timezone as fallback
+    expect(vtimezone[2]).toEqual(
+      expect.arrayContaining([
+        [
+          "standard",
+          [
+            ["tzoffsetfrom", {}, "utc-offset", "+00:00"],
+            ["tzoffsetto", {}, "utc-offset", "+00:00"],
+            ["tzname", {}, "text", "UTC"],
+            ["dtstart", {}, "date-time", "1970-01-01T00:00:00"],
+          ],
+          [],
+        ],
+      ])
+    );
+  });
+
+  it("handles valid timezone correctly", () => {
+    const mockEvent = {
+      uid: "event-valid-tz",
+      title: "Valid Timezone Event",
+      start: new Date("2025-07-23T10:00:00"),
+      end: new Date("2025-07-23T11:00:00"),
+      timezone: "Europe/Paris",
+      allday: false,
+      attendee: [],
+    };
+
+    const result = calendarEventToJCal(mockEvent as CalendarEvent);
+
+    expect(result[0]).toBe("vcalendar");
+    const [vevent, vtimezone] = result[2];
+    expect(vevent[0]).toBe("vevent");
+    expect(vtimezone[0]).toBe("vtimezone");
+
+    // Should use the specified timezone - check for Europe/Paris timezone components
+    expect(vtimezone[2]).toEqual(
+      expect.arrayContaining([
+        [
+          "daylight",
+          [
+            ["tzoffsetfrom", {}, "utc-offset", "+01:00"],
+            ["tzoffsetto", {}, "utc-offset", "+02:00"],
+            ["tzname", {}, "text", "CEST"],
+            ["dtstart", {}, "date-time", "1970-03-29T02:00:00"],
+            [
+              "rrule",
+              {},
+              "recur",
+              { byday: "-1SU", bymonth: 3, freq: "YEARLY" },
+            ],
+          ],
+          [],
+        ],
+        [
+          "standard",
+          [
+            ["tzoffsetfrom", {}, "utc-offset", "+02:00"],
+            ["tzoffsetto", {}, "utc-offset", "+01:00"],
+            ["tzname", {}, "text", "CET"],
+            ["dtstart", {}, "date-time", "1970-10-25T03:00:00"],
+            [
+              "rrule",
+              {},
+              "recur",
+              { byday: "-1SU", bymonth: 10, freq: "YEARLY" },
+            ],
+          ],
+          [],
+        ],
+      ])
+    );
+  });
 });
diff --git a/src/components/Calendar/Calendar.css b/src/components/Calendar/Calendar.css
index 704c32d..87e7712 100644
--- a/src/components/Calendar/Calendar.css
+++ b/src/components/Calendar/Calendar.css
@@ -1,12 +1,21 @@
-main {
+.App {
+  background-color: #f3f6f9;
   display: flex;
+  flex-direction: column;
+  justify-content: space-between;
+}
+.main-layout {
+  background-color: #fff;
   flex-direction: row;
+  height: calc(100vh - 90px);
+  display: flex;
 }
 
 .calendar {
   flex-grow: 1;
-  overflow: "hidden";
-  height: 90vh;
+  height: 100%;
+  overflow: hidden;
+  padding: 0 25px 0 10px;
 }
 
 .calendarListHeader {
@@ -16,38 +25,22 @@ main {
   margin-left: 25%;
 }
 .sidebar {
-  border-right: 2px gray;
+  border-right: 2px solid #f3f4f6;
   width: 20vw;
+  padding: 16px 25px;
 }
-
-.fc .fc-daygrid-day {
-  min-height: 10px !important; /* Default is ~40px */
-  height: 10px !important;
-  font-size: 0.75rem;
-}
-.fc .fc-timegrid-slot {
-  height: 60px !important; /* Default is ~40px */
-}
-
-.fc-timegrid-slot {
-  position: relative;
-}
-
 .declined-event {
   opacity: 0.7;
 }
 
-.tentative-event {
-}
-
 .needs-action-event {
   opacity: 0.7;
   border: dashed 1px #ffffff;
 }
 
 .fc .fc-timegrid-slot {
-  height: 30px !important;
-  min-height: 30px !important;
+  height: auto;
+  min-height: 54px !important;
 }
 
 .fc .fc-timegrid-slot-label {
@@ -74,14 +67,6 @@ main {
   overflow: hidden; /* Important: let FullCalendar handle internal scroll */
 }
 
-.fc-scroller-liquid-absolute {
-  overflow-y: auto !important; /* This targets the scrollable part */
-  max-height: calc(100vh - 100px); /* Adjust based on your header size */
-}
-.scrollgrid-section-header {
-  border: white;
-}
-
 /* Base container */
 .fc-daygrid-day-top {
   display: flex;
@@ -91,36 +76,6 @@ main {
   font-family: "Inter", sans-serif;
 }
 
-/* Day number */
-.fc-daygrid-day-top .fc-daygrid-day-number {
-  font-size: 1rem;
-  font-weight: 600;
-  line-height: 2;
-}
-
-/* Day name (e.g., MON) */
-.fc-daygrid-day-top small {
-  font-size: 0.75rem;
-  letter-spacing: 0.05em;
-  color: #94a3b8; /* slate gray */
-  text-transform: uppercase;
-}
-
-/* Today’s date highlight */
-.current-date {
-  background-color: orange;
-  color: white;
-  border-radius: 50%;
-  padding: 50px;
-}
-
-.fc .fc-col-header-cell,
-.fc .fc-scrollgrid table,
-.fc-theme-standard .fc-scrollgrid {
-  background: none;
-  border: none;
-}
-
 /* sidebar*/
 .sidebar-calendar {
   width: 280px;
@@ -207,3 +162,112 @@ main {
   margin-left: auto;
   margin-right: auto;
 }
+
+/* Custom main calendar view */
+.fc-header-toolbar.fc-toolbar.fc-toolbar-ltr {
+  /* display: none; */
+}
+.fc-theme-standard td,
+.fc-theme-standard th {
+  border: 1px solid #b8c1cc;
+  border-left: 0;
+}
+a.fc-timegrid-axis-cushion {
+  color: #243b55;
+  text-align: center;
+  font-family: Roboto;
+  font-size: 12.507px;
+  font-style: normal;
+  font-weight: 400;
+  line-height: 18.76px;
+  letter-spacing: 0.391px;
+}
+.fc-daygrid-day-top small {
+  color: #8c9caf;
+  font-size: 14px;
+  font-style: normal;
+  font-weight: 500;
+  line-height: 20px;
+  letter-spacing: 0.25px;
+}
+.fc-daygrid-day-top .fc-daygrid-day-number,
+span.fc-daygrid-day-number {
+  color: #243b55;
+  margin: 0 8px 0 0;
+  font-family: Roboto;
+  font-size: 28px;
+  font-style: normal;
+  font-weight: 400;
+  line-height: 36px;
+  position: relative;
+  width: 48px;
+  height: 48px;
+  line-height: 39px;
+}
+.fc-daygrid-day-top .fc-daygrid-day-number:after,
+span.fc-daygrid-day-number:after {
+  content: "";
+  z-index: -1;
+  border-radius: 50%;
+  width: 48px;
+  height: 48px;
+  position: absolute;
+  left: 0;
+  top: -1px;
+}
+span.fc-daygrid-day-number.current-date {
+  color: #fff;
+}
+span.fc-daygrid-day-number.current-date:after {
+  background-color: #f67e35;
+}
+td.fc-timegrid-slot.fc-timegrid-slot-label.fc-scrollgrid-shrink,
+td.fc-timegrid-slot.fc-timegrid-slot-label.fc-timegrid-slot-minor {
+  border: 0;
+}
+th.fc-timegrid-axis.fc-scrollgrid-shrink {
+  border: 0;
+  border-right: 1px solid #b8c1cc;
+}
+.fc .fc-timegrid-axis-cushion {
+  min-width: 70px;
+  max-width: 70px;
+  padding: 0;
+  text-align: left;
+}
+.fc .fc-timegrid-divider {
+  display: none;
+  height: 0;
+}
+.fc-timegrid-slot-label-cushion {
+  color: #aea9b1;
+  font-family: Roboto;
+  font-size: 14px;
+  font-style: normal;
+  font-weight: 400;
+  line-height: 20px;
+  letter-spacing: 0.25px;
+}
+th.fc-col-header-cell.fc-day {
+  border-right: 0;
+}
+.fc .fc-scrollgrid {
+  border: 0;
+}
+.fc .fc-timegrid-slot-label {
+  justify-content: flex-end;
+}
+.fc .fc-timegrid-slot-label .fc-timegrid-slot-label-frame {
+  position: relative;
+  transform: translate(-15px, -12px);
+}
+.fc .fc-timegrid-slot-label .fc-timegrid-slot-label-frame::after {
+  content: "";
+  z-index: -1;
+  background-color: #b8c1cc;
+  width: 10px;
+  height: 1px;
+  position: absolute;
+  top: 9.5px;
+  right: -15px;
+}
diff --git a/src/components/Calendar/Calendar.tsx b/src/components/Calendar/Calendar.tsx
index cfef63e..771218b 100644
--- a/src/components/Calendar/Calendar.tsx
+++ b/src/components/Calendar/Calendar.tsx
@@ -56,7 +56,8 @@ export default function CalendarApp() {
 
   const calendars = useAppSelector((state) => state.calendars.list);
   const pending = useAppSelector((state) => state.calendars.pending);
-  const userId = useAppSelector((state) => state.user.userData.openpaasId);
+  const userId =
+    useAppSelector((state) => state.user.userData?.openpaasId) ?? "";
   const selectPersonnalCalendars = createSelector(
     (state) => state.calendars,
     (calendars) =>
@@ -80,9 +81,21 @@ export default function CalendarApp() {
       );
     }
   });
-  const [selectedCalendars, setSelectedCalendars] = useState<string[]>(
-    Object.keys(calendars).filter((id) => id.split("/")[0] === userId)
-  );
+  const [selectedCalendars, setSelectedCalendars] = useState<string[]>([]);
+
+  // Auto-select personal calendars when first loaded
+  useEffect(() => {
+    if (
+      Object.keys(calendars).length > 0 &&
+      userId &&
+      selectedCalendars.length === 0
+    ) {
+      const personalCalendarIds = Object.keys(calendars).filter(
+        (id) => id.split("/")[0] === userId
+      );
+      setSelectedCalendars(personalCalendarIds);
+    }
+  }, [calendars, userId, selectedCalendars.length]);
 
   const calendarRange = getCalendarRange(selectedDate);
 
@@ -163,7 +176,7 @@ export default function CalendarApp() {
   }
 
   return (
-    <main>
+    <main className="main-layout">
       <div className="sidebar">
         <div className="calendar-label">
           <div className="calendar-label">
@@ -304,8 +317,10 @@ export default function CalendarApp() {
           weekNumbers
           weekNumberFormat={{ week: "long" }}
           slotDuration={"00:30:00"}
-          slotLabelInterval={"01:00:00"}
-          scrollTime={"08:00:00"}
+          slotLabelInterval={"00:30:00"}
+          scrollTime={new Date(Date.now() - 2 * 60 * 60 * 1000)
+            .toTimeString()
+            .slice(0, 5)}
           unselectAuto={false}
           allDayText=""
           slotLabelFormat={{
diff --git a/src/components/Calendar/CalendarSelection.tsx b/src/components/Calendar/CalendarSelection.tsx
index d526ed1..1734226 100644
--- a/src/components/Calendar/CalendarSelection.tsx
+++ b/src/components/Calendar/CalendarSelection.tsx
@@ -10,7 +10,6 @@ import { Calendars } from "../../features/Calendars/CalendarTypes";
 import MoreVertIcon from "@mui/icons-material/MoreVert";
 import IconButton from "@mui/material/IconButton";
 import Checkbox from "@mui/material/Checkbox";
-import Button from "@mui/material/Button";
 import ExpandMoreIcon from "@mui/icons-material/ExpandMore";
 
 function CalendarAccordion({
@@ -34,8 +33,8 @@ function CalendarAccordion({
 }) {
   const allCalendars = useAppSelector((state) => state.calendars.list);
 
-  if (calendars.length === 0) return null;
   const [expended, setExpended] = useState(defaultExpanded);
+  if (calendars.length === 0) return null;
 
   return (
     <Accordion defaultExpanded={defaultExpanded} expanded={expended}>
@@ -81,7 +80,8 @@ export default function CalendarSelection({
   selectedCalendars: string[];
   setSelectedCalendars: Function;
 }) {
-  const userId = useAppSelector((state) => state.user.userData.openpaasId);
+  const userId =
+    useAppSelector((state) => state.user.userData?.openpaasId) ?? "";
   const calendars = useAppSelector((state) => state.calendars.list);
 
   const personnalCalendars = Object.keys(calendars).filter(
diff --git a/src/components/Menubar/Menubar.css b/src/components/Menubar/Menubar.css
index aafc6df..2fcffb0 100644
--- a/src/components/Menubar/Menubar.css
+++ b/src/components/Menubar/Menubar.css
@@ -42,7 +42,8 @@
   padding: 0.5rem;
   width: 100%;
   z-index: 1000;
-  height: 7vh;
+  height: 80px;
+  background-color: #fff;
 }
 
 .menubar-item {
diff --git a/src/components/Menubar/Menubar.tsx b/src/components/Menubar/Menubar.tsx
index cc3ee09..3850f71 100644
--- a/src/components/Menubar/Menubar.tsx
+++ b/src/components/Menubar/Menubar.tsx
@@ -48,14 +48,18 @@ export function Menubar() {
           <Avatar
             sx={{
               bgcolor: stringToColor(
-                user.family_name ? user.family_name : user.email
+                user && user.family_name
+                  ? user.family_name
+                  : user && user.email
+                    ? user.email
+                    : ""
               ),
             }}
             sizes="large"
           >
-            {user.name && user.family_name
+            {user?.name && user?.family_name
               ? `${user.name[0]}${user.family_name[0]}`
-              : user.email[0]}
+              : (user?.email?.[0] ?? "")}
           </Avatar>
         </div>
       </header>
diff --git a/src/features/Calendars/CalendarModal.tsx b/src/features/Calendars/CalendarModal.tsx
index 623716b..d53c3c1 100644
--- a/src/features/Calendars/CalendarModal.tsx
+++ b/src/features/Calendars/CalendarModal.tsx
@@ -30,7 +30,7 @@ function CalendarPopover({
 }) {
   const dispatch = useAppDispatch();
   const userId =
-    useAppSelector((state) => state.user.userData.openpaasId) ?? "";
+    useAppSelector((state) => state.user.userData?.openpaasId) ?? "";
   const [name, setName] = useState(calendar?.name ?? "");
   const [description, setDescription] = useState(calendar?.description ?? "");
   const [color, setColor] = useState(calendar?.color ?? "");
diff --git a/src/features/Events/EventDisplay.tsx b/src/features/Events/EventDisplay.tsx
index 5bc56ab..0c51855 100644
--- a/src/features/Events/EventDisplay.tsx
+++ b/src/features/Events/EventDisplay.tsx
@@ -74,7 +74,7 @@ export default function EventDisplayModal({
   );
 
   const userPersonnalCalendars: Calendars[] = calendars.filter(
-    (c) => c.id?.split("/")[0] === user.userData.openpaasId
+    (c) => c.id?.split("/")[0] === user.userData?.openpaasId
   );
 
   // Form state
@@ -97,7 +97,7 @@ export default function EventDisplayModal({
   const [timezone, setTimezone] = useState(event?.timezone ?? "UTC");
   const [newCalId, setNewCalId] = useState(event?.calId);
   const [calendarid, setCalendarid] = useState(
-    calId.split("/")[0] === user.userData.openpaasId
+    calId.split("/")[0] === user.userData?.openpaasId
       ? userPersonnalCalendars.findIndex((cal) => cal.id === calId)
       : calendars.findIndex((cal) => cal.id === calId)
   );
@@ -198,7 +198,7 @@ export default function EventDisplayModal({
   };
 
   const calList =
-    calId.split("/")[0] === user.userData.openpaasId
+    calId.split("/")[0] === user.userData?.openpaasId
       ? Object.keys(userPersonnalCalendars).map((calendar, index) => (
           <MenuItem key={index} value={index}>
             <Typography variant="body2">
diff --git a/src/features/Events/EventModal.tsx b/src/features/Events/EventModal.tsx
index 92aa3ae..d55cb9c 100644
--- a/src/features/Events/EventModal.tsx
+++ b/src/features/Events/EventModal.tsx
@@ -46,7 +46,8 @@ function EventPopover({
   const dispatch = useAppDispatch();
 
   const organizer = useAppSelector((state) => state.user.organiserData);
-  const userId = useAppSelector((state) => state.user.userData.openpaasId);
+  const userId =
+    useAppSelector((state) => state.user.userData?.openpaasId) ?? "";
   const selectPersonnalCalendars = createSelector(
     (state) => state.calendars,
     (calendars) =>
diff --git a/src/features/Events/eventUtils.ts b/src/features/Events/eventUtils.ts
index c92ec07..e0eb0fc 100644
--- a/src/features/Events/eventUtils.ts
+++ b/src/features/Events/eventUtils.ts
@@ -234,8 +234,17 @@ export function calendarEventToJCal(
     ]);
   });
 
+  const timezoneData = TIMEZONES.zones[event.timezone];
+  if (!timezoneData) {
+    const vtimezone = new ICAL.Timezone({
+      component: TIMEZONES.zones["Etc/UTC"].ics,
+      tzid: "Etc/UTC",
+    });
+    return ["vcalendar", [], [vevent, vtimezone.component.jCal]];
+  }
+
   const vtimezone = new ICAL.Timezone({
-    component: TIMEZONES.zones[event.timezone].ics,
+    component: timezoneData.ics,
     tzid: event.timezone,
   });
   return ["vcalendar", [], [vevent, vtimezone.component.jCal]];
diff --git a/src/features/User/HandleLogin.tsx b/src/features/User/HandleLogin.tsx
index e591078..7e964ab 100644
--- a/src/features/User/HandleLogin.tsx
+++ b/src/features/User/HandleLogin.tsx
@@ -2,7 +2,6 @@ import React, { useEffect } from "react";
 import { useAppDispatch, useAppSelector } from "../../app/hooks";
 import { Auth } from "./oidcAuth";
 import { Loading } from "../../components/Loading/Loading";
-import { Error } from "../../components/Error/Error";
 import { push } from "redux-first-history";
 import { redirectTo } from "../../utils/apiUtils";
 import { getOpenPaasUserDataAsync, setTokens, setUserData } from "./userSlice";
@@ -27,7 +26,7 @@ export function HandleLogin() {
           dispatch(setUserData(savedUser));
           dispatch(getOpenPaasUserDataAsync());
           dispatch(getCalendarsListAsync());
-          dispatch(push("/"));
+          dispatch(push("/calendar"));
           return;
         }