diff --git a/__test__/components/Calendar.test.tsx b/__test__/components/Calendar.test.tsx
index ed3dd23..f699d55 100644
--- a/__test__/components/Calendar.test.tsx
+++ b/__test__/components/Calendar.test.tsx
@@ -135,7 +135,7 @@ describe("CalendarSelection", () => {
           },
         },
       },
-      pending: false,
+      pending: true,
     },
   };
   it("renders calendars", async () => {
@@ -340,7 +340,7 @@ describe("calendar Availability search", () => {
           events: {},
         },
       },
-      pending: false,
+      pending: true,
       templist: {},
     },
   };
@@ -495,12 +495,20 @@ describe("calendar Availability search", () => {
   }, 15000);
 
   it("BUGFIX: can untoggle all calendar.personal", async () => {
+    jest
+      .spyOn(calendarDetailThunks, "getCalendarDetailAsync")
+      .mockImplementation(
+        () =>
+          ({
+            type: "getCalendarDetailAsync",
+            unwrap: () => Promise.resolve({}),
+          }) as any
+      );
     await act(async () =>
       renderWithProviders(<CalendarTestWrapper />, {
         user: preloadedState.user,
         calendars: {
           list: { "user1/cal1": preloadedState.calendars.list["user1/cal1"] },
-          pending: false,
         },
       })
     );
@@ -572,8 +580,8 @@ describe("calendar Availability search", () => {
       calendarApi.changeView("dayGridMonth");
       fireEvent.click(screen.getByTestId("ChevronRightIcon"));
     });
-    expect(spy).toHaveBeenCalledTimes(4);
-    const callArgs = spy.mock.calls[3][0];
+    expect(spy).toHaveBeenCalledTimes(2);
+    const callArgs = spy.mock.calls[1][0];
     expect(callArgs.calId).toBe("user1/cal1");
 
     const startDate = new Date(
@@ -621,10 +629,13 @@ describe("calendar Availability search", () => {
 
       const spy = jest
         .spyOn(calendarDetailThunks, "getCalendarDetailAsync")
-        .mockImplementation(() => ({
-          type: "getCalendarDetailAsync",
-          unwrap: () => Promise.resolve({}),
-        })) as any;
+        .mockImplementation(
+          () =>
+            ({
+              type: "getCalendarDetailAsync",
+              unwrap: () => Promise.resolve({}),
+            }) as any
+        );
 
       await act(async () => {
         renderWithProviders(
@@ -675,10 +686,13 @@ describe("calendar Availability search", () => {
 
       const spy = jest
         .spyOn(calendarDetailThunks, "getCalendarDetailAsync")
-        .mockImplementation(() => ({
-          type: "getCalendarDetailAsync",
-          unwrap: () => Promise.resolve({}),
-        })) as any;
+        .mockImplementation(
+          () =>
+            ({
+              type: "getCalendarDetailAsync",
+              unwrap: () => Promise.resolve({}),
+            }) as any
+        );
 
       await act(async () => {
         renderWithProviders(
@@ -708,10 +722,13 @@ describe("calendar Availability search", () => {
     it("does not make duplicate API calls for same calendar and range", async () => {
       const spy = jest
         .spyOn(calendarDetailThunks, "getCalendarDetailAsync")
-        .mockImplementation(() => ({
-          type: "getCalendarDetailAsync",
-          unwrap: () => Promise.resolve({}),
-        })) as any;
+        .mockImplementation(
+          () =>
+            ({
+              type: "getCalendarDetailAsync",
+              unwrap: () => Promise.resolve({}),
+            }) as any
+        );
 
       await act(async () => {
         renderWithProviders(
diff --git a/src/components/Calendar/Calendar.tsx b/src/components/Calendar/Calendar.tsx
index ea3324d..00887d6 100644
--- a/src/components/Calendar/Calendar.tsx
+++ b/src/components/Calendar/Calendar.tsx
@@ -13,6 +13,7 @@ import {
 } from "@/utils/dateUtils";
 import { extractEventBaseUuid } from "@/utils/extractEventBaseUuid";
 import { setSelectedCalendars as setSelectedCalendarsToStorage } from "@/utils/storage/setSelectedCalendars";
+import { useSelectedCalendars } from "@/utils/storage/useSelectedCalendars";
 import { browserDefaultTimeZone } from "@/utils/timezone";
 import { CalendarApi, DateSelectArg } from "@fullcalendar/core";
 import frLocale from "@fullcalendar/core/locales/fr";
@@ -76,11 +77,14 @@ export default function CalendarApp({
     (state) => state.settings.hideDeclinedEvents
   );
   const calendars = useAppSelector((state) => state.calendars.list);
+  const isPending = useAppSelector((state) => state.calendars.pending);
   const displayWeekNumbers = useAppSelector(
     (state) => state.settings.displayWeekNumbers
   );
   const tempcalendars = useAppSelector((state) => state.calendars.templist);
-  const [selectedCalendars, setSelectedCalendars] = useState<string[]>([]);
+  const storedCalendars = useSelectedCalendars();
+  const [selectedCalendars, setSelectedCalendars] =
+    useState<string[]>(storedCalendars);
 
   const calendarLightSignature = useMemo(() => {
     return Object.values(calendars || {})
@@ -253,6 +257,8 @@ export default function CalendarApp({
   }, [rangeKey]);
 
   useEffect(() => {
+    if (isPending) return;
+
     if (!rangeKey || sortedSelectedCalendars.length === 0) {
       activeLoadCompletedRef.current = true;
       setActiveLoadCompleted(true);
@@ -320,8 +326,7 @@ export default function CalendarApp({
   }, [dispatch, rangeKey, sortedSelectedCalendars, rangeStart, rangeEnd]);
 
   useEffect(() => {
-    if (!rangeKey || !activeLoadCompleted) return;
-
+    if (!rangeKey || !activeLoadCompleted || isPending) return;
     const hiddenCalendars = calendarIds
       .filter((id) => !selectedCalendars.includes(id))
       .filter((id) => {
@@ -355,6 +360,7 @@ export default function CalendarApp({
     rangeStart,
     rangeEnd,
     activeLoadCompleted,
+    isPending,
   ]);
 
   const calendarsWithClearedCache = useMemo(() => {
@@ -369,6 +375,7 @@ export default function CalendarApp({
   const processedCacheClearRef = useRef<Record<string, number>>({});
 
   useEffect(() => {
+    if (isPending) return;
     calendarsWithClearedCache.forEach(({ id, cleared }) => {
       if (processedCacheClearRef.current[id] === cleared) {
         return;
@@ -397,7 +404,14 @@ export default function CalendarApp({
           prefetchedCalendarsRef.current[id] = "";
         });
     });
-  }, [calendarsWithClearedCache, dispatch, rangeKey, rangeStart, rangeEnd]);
+  }, [
+    calendarsWithClearedCache,
+    dispatch,
+    rangeKey,
+    rangeStart,
+    rangeEnd,
+    isPending,
+  ]);
 
   useEffect(() => {
     const currentIds = new Set(tempCalendarIds);
diff --git a/src/features/Calendars/CalendarSlice.ts b/src/features/Calendars/CalendarSlice.ts
index 17353e0..83b32fb 100644
--- a/src/features/Calendars/CalendarSlice.ts
+++ b/src/features/Calendars/CalendarSlice.ts
@@ -28,7 +28,7 @@ const CalendarSlice = createSlice({
   initialState: {
     list: {} as Record<string, Calendar>,
     templist: {} as Record<string, Calendar>,
-    pending: false,
+    pending: true,
     error: null as string | null,
   } as {
     list: Record<string, Calendar>;
diff --git a/src/utils/storage/useSelectedCalendars.ts b/src/utils/storage/useSelectedCalendars.ts
index 7689f0d..180324c 100644
--- a/src/utils/storage/useSelectedCalendars.ts
+++ b/src/utils/storage/useSelectedCalendars.ts
@@ -2,6 +2,7 @@ import { useEffect, useState } from "react";
 
 export function useSelectedCalendars(): string[] {
   const [calendars, setCalendars] = useState<string[]>(() => {
+    if (typeof window === "undefined") return [];
     try {
       return JSON.parse(localStorage.getItem("selectedCalendars") ?? "[]");
     } catch {
@@ -10,6 +11,8 @@ export function useSelectedCalendars(): string[] {
   });
 
   useEffect(() => {
+    if (typeof window === "undefined") return;
+
     const onStorage = (e: StorageEvent) => {
       if (e.key === "selectedCalendars") {
         try {
diff --git a/src/websocket/WebSocketGate.tsx b/src/websocket/WebSocketGate.tsx
index 6cefb3d..cb73e00 100644
--- a/src/websocket/WebSocketGate.tsx
+++ b/src/websocket/WebSocketGate.tsx
@@ -17,6 +17,7 @@ export function WebSocketGate() {
   );
 
   const [isSocketOpen, setIsSocketOpen] = useState(false);
+  const isPending = useAppSelector((state) => state.calendars.pending);
 
   const calendarList = useSelectedCalendars();
   const tempCalendarList = Object.keys(
@@ -73,13 +74,15 @@ export function WebSocketGate() {
 
   // Register using a diff with previous calendars
   useEffect(() => {
+    if (isPending) return;
+
     syncCalendarRegistrations(
       isSocketOpen,
       socketRef,
       calendarList,
       previousCalendarListRef
     );
-  }, [isSocketOpen, calendarList]);
+  }, [isSocketOpen, calendarList, isPending]);
 
   useEffect(() => {
     syncCalendarRegistrations(