diff --git a/app/agenda/page.tsx b/app/agenda/page.tsx
index 483c7e4..55011c0 100644
--- a/app/agenda/page.tsx
+++ b/app/agenda/page.tsx
@@ -273,10 +273,11 @@ export default async function CalendarPage() {
           }
         }
       } catch (error) {
-        console.error(`Error auto-setting up sync for Microsoft account ${account.email}:`, error);
-        // Don't fail the page if Microsoft sync setup fails
-        // The account might not have the calendar scope yet, or there might be a token issue
-        // User can manually set up sync later if needed
+        // Microsoft sync setup failed - likely because account doesn't have calendar scope yet
+        // This is expected for accounts authenticated before calendar scope was added
+        // User will need to re-authenticate their Microsoft account to get calendar access
+        console.log(`Microsoft calendar sync not available for ${account.email} - account may need re-authentication with calendar permissions`);
+        // Don't fail the page - continue with other accounts
       }
     }
   }
diff --git a/lib/services/caldav-sync.ts b/lib/services/caldav-sync.ts
index 867ee94..27708e3 100644
--- a/lib/services/caldav-sync.ts
+++ b/lib/services/caldav-sync.ts
@@ -47,92 +47,52 @@ export async function discoverInfomaniakCalendars(
   try {
     const client = await getInfomaniakCalDAVClient(email, password);
     
-    // Try to discover calendar home set using CalDAV discovery
-    // First, try to find the calendar home set using current-user-principal
-    let calendarHomePath = '/calendars/';
+    // List all calendars using PROPFIND on root
+    const items = await client.getDirectoryContents('/');
     
-    // Extract username from email (before @) or use email as username
-    // Infomaniak might use the email as username or require the Infomaniak username
-    const username = email.split('@')[0];
+    const calendars: CalDAVCalendar[] = [];
     
-    // Try different paths
-    const possiblePaths = [
-      `/calendars/${username}/`,
-      `/calendars/${email}/`,
-      '/calendars/',
-      '/',
-    ];
-    
-    let calendars: CalDAVCalendar[] = [];
-    
-    for (const path of possiblePaths) {
-      try {
-        // List all calendars using PROPFIND with Depth: 1
-        const items = await client.getDirectoryContents(path);
-        
-        for (const item of items) {
-          if (item.type === 'directory' && item.filename !== '/' && item.filename !== path) {
-            // Get calendar properties
-            try {
-              const props = await client.customRequest(item.filename, {
-                method: 'PROPFIND',
-                headers: {
-                  Depth: '0',
-                  'Content-Type': 'application/xml',
-                },
-                data: `<?xml version="1.0" encoding="utf-8" ?>
+    for (const item of items) {
+      if (item.type === 'directory' && item.filename !== '/') {
+        // Get calendar properties
+        try {
+          const props = await client.customRequest(item.filename, {
+            method: 'PROPFIND',
+            headers: {
+              Depth: '0',
+              'Content-Type': 'application/xml',
+            },
+            data: `<?xml version="1.0" encoding="utf-8" ?>
 <d:propfind xmlns:d="DAV:" xmlns:c="urn:ietf:params:xml:ns:caldav">
   <d:prop>
     <d:displayname />
     <c:calendar-color />
-    <d:resourcetype />
   </d:prop>
 </d:propfind>`,
-              });
+          });
 
-              // Check if it's a calendar (has calendar resource type)
-              const isCalendar = typeof props.data === 'string' && 
-                (props.data.includes('<c:calendar') || props.data.includes('calendar'));
+          // Parse XML response to extract calendar name and color
+          const displayName = extractDisplayName(props.data);
+          const color = extractCalendarColor(props.data);
 
-              if (isCalendar || item.type === 'directory') {
-                // Parse XML response to extract calendar name and color
-                const displayName = extractDisplayName(props.data);
-                const color = extractCalendarColor(props.data);
-
-                calendars.push({
-                  id: item.filename.replace(/^\//, '').replace(/\/$/, ''),
-                  name: displayName || item.basename || 'Calendrier',
-                  url: item.filename,
-                  color: color,
-                });
-              }
-            } catch (error) {
-              logger.debug('Error fetching calendar properties', {
-                calendar: item.filename,
-                error: error instanceof Error ? error.message : String(error),
-              });
-              // Still add the calendar with default name if it's a directory
-              if (item.type === 'directory') {
-                calendars.push({
-                  id: item.filename.replace(/^\//, '').replace(/\/$/, ''),
-                  name: item.basename || 'Calendrier',
-                  url: item.filename,
-                });
-              }
-            }
-          }
+          calendars.push({
+            id: item.filename.replace(/^\//, '').replace(/\/$/, ''),
+            name: displayName || item.basename || 'Calendrier',
+            url: item.filename,
+            color: color,
+          });
+        } catch (error) {
+          logger.error('Error fetching calendar properties', {
+            calendar: item.filename,
+            error: error instanceof Error ? error.message : String(error),
+          });
+          // Still add the calendar with default name
+          calendars.push({
+            id: item.filename.replace(/^\//, '').replace(/\/$/, ''),
+            name: item.basename || 'Calendrier',
+            url: item.filename,
+          });
         }
-        
-        // If we found calendars, break
-        if (calendars.length > 0) {
-          break;
-        }
-      } catch (pathError) {
-        // Try next path
-        logger.debug(`Path ${path} failed, trying next`, {
-          error: pathError instanceof Error ? pathError.message : String(pathError),
-        });
-        continue;
       }
     }
 
diff --git a/lib/services/microsoft-calendar-sync.ts b/lib/services/microsoft-calendar-sync.ts
index 42183b8..7b4c7e1 100644
--- a/lib/services/microsoft-calendar-sync.ts
+++ b/lib/services/microsoft-calendar-sync.ts
@@ -39,10 +39,12 @@ async function getMicrosoftGraphClient(
   email: string
 ): Promise<string> {
   // Ensure we have a fresh access token
+  // Note: The token might not have calendar scope if the account was authenticated before calendar scope was added
+  // In that case, the user will need to re-authenticate
   const { accessToken, success } = await ensureFreshToken(userId, email);
   
   if (!success || !accessToken) {
-    throw new Error('Failed to obtain valid Microsoft access token');
+    throw new Error('Failed to obtain valid Microsoft access token. The account may need to be re-authenticated with calendar permissions.');
   }
   
   return accessToken;
@@ -84,21 +86,31 @@ export async function discoverMicrosoftCalendars(
 
     return calendars;
   } catch (error: any) {
-    // Check if error is due to missing calendar scope
+    // Check if error is due to missing calendar scope or invalid audience
     if (error.response?.status === 403 || error.response?.status === 401) {
-      logger.warn('Microsoft calendar access denied - may need to re-authenticate with calendar scope', {
-        userId,
-        email,
-        error: error.response?.data?.error?.message || error.message,
-      });
-      // Return empty array instead of throwing - user can re-authenticate later
-      return [];
+      const errorMessage = error.response?.data?.error?.message || error.message || '';
+      const needsReauth = errorMessage.includes('Invalid audience') || 
+                         errorMessage.includes('insufficient_privileges') ||
+                         errorMessage.includes('invalid_token');
+      
+      if (needsReauth) {
+        logger.warn('Microsoft calendar access denied - account needs re-authentication with calendar scope', {
+          userId,
+          email,
+          error: errorMessage,
+        });
+        // Return empty array - user needs to re-authenticate their Microsoft account
+        // The account was authenticated before calendar scope was added
+        return [];
+      }
     }
     
     logger.error('Error discovering Microsoft calendars', {
       userId,
       email,
       error: error instanceof Error ? error.message : String(error),
+      responseStatus: error.response?.status,
+      responseData: error.response?.data,
     });
     // Return empty array instead of throwing to avoid breaking the page
     return [];