How to fix calendar sync failures after changing your Microsoft 365 password

Summary

This guide helps you troubleshoot and resolve: How to fix calendar sync failures after changing your Microsoft 365 password. Follow the steps below to fix the issue.

Common Causes

Changing your Microsoft 365 password can break the link between Outlook and any external calendar services you use, such as Google Calendar. This article walks you through the quickest way to restore synchronisation, then provides detailed instructions for both Windows and macOS users, and finishes with extra troubleshooting tips.

Quick Fix Steps

1. Close Outlook completely.
2. Open Windows Credential Manager (or Keychain Access on macOS) and delete any entries that contain MicrosoftOffice or Outlook.
3. Restart Outlook; you will be prompted to enter your new Microsoft 365 password. Type it in and select Remember my credentials.
4. Open your Google Calendar sync tool (e.g., Outlook Google Calendar Sync) and re‑authenticate using the same new password.
5. Wait a few minutes for the first sync cycle, then verify that events appear in both calendars.

Detailed Instructions

1. Update Outlook (Windows)

1. Press Ctrl + Shift + Esc to open the Task Manager and end any Outlook.exe processes.
2. Press Win + R, type control keymgr.dll and press Enter to launch Credential Manager.
3. Click Windows Credentials, locate entries that start with MicrosoftOffice or Office16, and choose Remove.
4. Open Outlook again. When prompted, enter your new Microsoft 365 password and tick Remember my credentials.
5. Navigate to File → Account Settings → Account Settings, select your Microsoft 365 account and click Repair to force a re‑authentication.

2. Update Outlook (macOS)

1. Quit Outlook via Outlook → Quit Outlook or Cmd + Q.
2. Open Keychain Access from Applications → Utilities.
3. Search for “MicrosoftOffice” and delete any matching items.
4. Re‑open Outlook; you’ll see a sign‑in window. Enter your new password and, if asked, approve any multi‑factor authentication prompt.
5. Go to Outlook → Preferences → Accounts, select your Microsoft 365 account and click Advanced. Ensure the Sync all events option is checked.

3. Re‑authenticate Google Calendar Sync Tool

1. Open your sync application (e.g., Outlook Google Calendar Sync).
2. In the Settings tab, click the Authenticate button next to the Google account.
3. When the Google sign‑in page appears, log in with the same Microsoft 365 credentials (if using single sign‑on) or your Google account as appropriate.
4. After successful authentication, click Save Settings and then Start Sync.
5. Check the sync log for any errors; a green “Sync completed” message means the connection is restored.

4. Verify Calendar Sync

• In Outlook, open the Calendar view and create a test event titled “Sync Test”. Set the time for a few minutes ahead.
• Switch to Google Calendar (web or app) and confirm the event appears.
• If the event is missing, run another manual sync from the sync tool and re‑check.

Troubleshooting

Common Issues

• Sync stops after the first run – often caused by outdated cached credentials. Repeat the Credential Manager/Keychain steps.
• Authentication errors – ensure your Microsoft 365 account isn’t locked and that any required multi‑factor authentication (MFA) is completed.
• Events disappear – check that the sync direction is set correctly (e.g., Outlook → Google, Google → Outlook, or bidirectional).

Advanced Checks

1. Open a web browser and sign in to Microsoft 365 portal to confirm your new password works.
2. Visit Google Workspace Status Dashboard to verify there are no service outages.
3. In Windows, run netsh winsock reset from an elevated Command Prompt and reboot – this can resolve hidden network stack issues.
4. On macOS, clear Outlook’s cache by deleting the folder ~/Library/Group Containers/UBF8T346G9.Office/Outlook/Outlook 15 Profiles/Main Profile (ensure you have a backup first).

When to Seek Further Help

If you have followed all steps and the calendars still do not sync, please Open a Ticket and include the following details:

• Operating system and version (e.g., Windows 10 22H2, macOS 14.2)
• Outlook version (File → Office Account → About Outlook)
• Name and version of the Google sync tool you are using
• Any error messages from the sync log

Still Having Issues?