9 reasons why Calendar doesn’t work in Windows 10 (and how to fix it)

Start here: if your Calendar app won’t open, won’t sync, or is missing events, the most likely cause is a mix of account, app, or system configuration problems — in short, Calendar doesn’t work in Windows 10. This article explains common causes (network, account, app corruption, permissions, time settings, system files, and updates) and gives step‑by‑step fixes so you can get your calendar working again.

You’ll learn quick triage steps, detailed repairs (including PowerShell commands, Settings paths, and useful tips), and when to escalate to support.

Key Takeaway

Most Calendar problems in Windows 10 are caused by account sync issues, app corruption, or incorrect permissions; start by checking your account and sync settings, then repair or reset the Mail and Calendar app, and finally run system file checks and update Windows if problems persist.

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Quick Fix Guide

Quick Fix Guide

Reason for the Problem	Quick Solution
1. Internet or sync connection issues	Check network, toggle sync, and re‑sync the account.
2. Account missing or expired credentials	Re-add the account or update the password in Settings > Accounts or Mail & Calendar app.
3. Outdated Calendar/Mail app	Update via Microsoft Store > Downloads and updates.
4. Corrupted app data	Repair or Reset the app in Settings > Apps > Apps & features.
5. Calendar permissions blocked	Allow Calendar access in Settings > Privacy > Calendar and enable background apps.
6. Wrong date, time, or time zone	Fix in Settings > Time & Language > Date & time or enable automatic time.
7. Server or provider issues (Exchange, Google, iCloud)	Check provider status and reconfigure sync settings for that account.
8. Corrupted system files or profile	Run sfc /scannow and DISM; create a new Windows user to test.
9. Windows bug or outdated OS	Install Windows Updates and reinstall the Mail and Calendar app if needed.

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Detailed Fixes for “tu mets ici le problème du 9 reasons why Calendar doesn’t work in Windows 10 (and how to fix it)”.

1. Internet or sync connection issues

Why this causes the problem:
Calendar needs network access to sync events from Exchange, Google, iCloud, or other providers. If your PC has poor connectivity, a proxy, or VPN causing interference, sync will fail or be intermittent.

Step-by-step solution:

1. Verify internet connectivity: open a browser and load several websites.
2. Disable VPN/proxy temporarily: Settings > Network & Internet > Proxy and turn Use a proxy server off (if set).
3. Toggle airplane mode off/on: Action Center (bottom right) > click Airplane mode.
4. In the Calendar app, open Settings (gear) > Manage Accounts, select the account, then click Sync or Change mailbox sync settings and press Sync.
5. If using corporate network, confirm with IT that firewall rules allow Exchange/ActiveSync.

Tips:

• If sync works on another device (phone), the issue is PC-specific.
• Run ping google.com in Command Prompt to confirm packet flow.

2. Account missing or expired credentials

Why this causes the problem:
If your account password changed or your account was removed, Calendar can’t access the remote server and will show no events or a sync error.

Step-by-step solution:

1. Open Settings > Accounts > Email & accounts to see saved accounts.
2. In the Calendar app: Settings (gear) > Manage Accounts. Select the account and choose Change settings or Change mailbox sync settings.
3. Re-enter the password if prompted. If authentication fails, remove and re‑add the account:
   • In Mail & Calendar: Manage Accounts > Add account and follow provider prompts.
4. For Microsoft accounts, visit https://account.microsoft.com to ensure no security blocks; verify two‑factor prompts on other devices.

Notes:

• For Exchange/Office 365, ensure your admin hasn’t disabled the account or changed policies.

3. Outdated Calendar/Mail app

Why this causes the problem:
Bugs fixed in newer releases can cause crashes or sync failures; running an outdated app can lead to compatibility issues.

Step-by-step solution:

1. Open Microsoft Store.
2. Click the profile icon > Downloads and updates.
3. Click Get updates or find Mail and Calendar and update it.
4. Restart the PC after updating.

Tip:

• If Store fails to update, run wsreset.exe (type this in Start and run) to clear the Store cache.

4. Corrupted app data

Why this causes the problem:
App files or cache can become corrupted causing crashes, missing events, or failure to open.

Step-by-step solution:

1. Open Settings > Apps > Apps & features.
2. Scroll to Mail and Calendar, click it, then Advanced options.
3. First choose Repair (keeps data). Test the app.
4. If problem persists, click Reset (this clears app data).
5. Reopen Mail and Calendar and re-add accounts if needed.

PowerShell reinstall (advanced):

1. Open PowerShell as Administrator.
2. Run:
   • Get-AppxPackage Microsoft.windowscommunicationsapps | Remove-AppxPackage
3. Reinstall from Microsoft Store or re-register with:
   • Get-AppxPackage -allusers Microsoft.windowscommunicationsapps | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register “$($_.InstallLocation)\AppXManifest.xml”}

Warning:

• Reinstalling can require reconfiguring accounts.

5. Calendar permissions blocked

Why this causes the problem:
Windows privacy settings can block apps from accessing calendar data or running in the background, preventing sync.

Step-by-step solution:

1. Open Settings > Privacy > Calendar and ensure Allow apps to access your calendar is On.
2. Scroll the list and turn on access for Mail and Calendar (or the specific app).
3. Go to Settings > Privacy > Background apps and ensure Mail and Calendar is allowed to run in the background.
4. Test sync after enabling permissions.

Tip:

• Some security/cleanup utilities may toggle these settings; re-check after using them.

6. Wrong date, time, or time zone

Why this causes the problem:
Authentication and server sync rely on correct time — a wrong time or time zone can cause login failures and incorrect event times.

Step-by-step solution:

1. Open Settings > Time & Language > Date & time.
2. Turn Set time automatically and Set time zone automatically on.
3. If you must set manually, ensure the time zone is correct; click Sync now under Synchronize your clock.
4. Restart Calendar and check events for correct times.

Tip:

• For domain-joined machines, domain time sync may override local settings — contact IT if needed.

7. Server or provider issues (Exchange, Google, iCloud)

Why this causes the problem:
Sometimes the issue isn’t Windows — providers can have outages, changed APIs (e.g., OAuth changes), or require app-specific passwords.

Step-by-step solution:

1. Check provider status pages: Google Workspace status, Outlook.com status, iCloud System Status.
2. For Google: ensure you use the recommended OAuth flow (re‑add account via the Mail & Calendar add account wizard).
3. For iCloud: ensure app‑specific passwords are generated for third‑party apps and that two‑factor authentication is configured correctly.
4. Remove and re-add the account in Calendar so the newest authentication flow is used.

Notes:

• Corporate Exchange servers may require certificate or policy updates — check with admin.

8. Corrupted system files or user profile

Why this causes the problem:
Damaged system files or profile settings can prevent apps from accessing necessary services causing unusual behavior.

Step-by-step solution:

1. Open Command Prompt as Administrator and run:
   • sfc /scannow
2. If SFC finds issues it cannot fix, run DISM:
   • DISM /Online /Cleanup-Image /RestoreHealth
3. After DISM finishes, run sfc /scannow again.
4. Test Calendar. If still failing, create a new Windows user to see if the problem is profile-specific:
   • Settings > Accounts > Family & other users > Add someone else to this PC.
5. Log in as the new user and test the Calendar app.

Tip:

• Keep backups of important data before making profile changes.

9. Windows bug or outdated OS

Why this causes the problem:
OS-level bugs or missing updates can break app behavior. Microsoft often releases patches that fix Calendar/Mail stability.

Step-by-step solution:

1. Open Settings > Update & Security > Windows Update.
2. Click Check for updates and install all pending updates. Restart if prompted.
3. After updates, test Calendar.
4. If a recent Windows update introduced the issue, consider uninstalling that update: Settings > Update & Security > View update history > Uninstall updates.
5. If widespread, search Microsoft support forums for known issues and hotfixes.

Notes:

• Keep Windows and the Microsoft Store app updated to reduce compatibility problems.

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Maintenance and prevention

• Regularly update Windows and apps via Windows Update and Microsoft Store.
• Periodically backup important calendar data (export to .ics from provider web UI).
• Use standard authentication methods (OAuth) where possible; avoid deprecated protocols.
• Limit third‑party cleanup tools that change privacy or background app settings.
• If you manage devices in an organization, document policies that might block Mail/Calendar access.

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FAQ

How can I export my calendar events before attempting big fixes?

Open the web interface for your calendar provider (Outlook.com, Google Calendar, iCloud), use the export/backup option to download an .ics file, or from Exchange/Outlook desktop use File > Open & Export > Import/Export.

My Calendar app shows events but notifications aren’t working — what should I check?

Confirm notifications: Settings > System > Notifications & actions, ensure Mail and Calendar notifications are enabled and prioritized; also check Settings > Privacy > Background apps to allow background activity.

Can antivirus or firewall software block Calendar sync?

Yes. Temporarily disable third‑party firewall/antivirus and test. If allowed, add exceptions for Mail and Calendar or permit the Outlook/Exchange ports used by your provider.

Is it safe to use PowerShell commands to remove and reinstall apps?

Yes if you follow instructions; removing and re‑registering built‑in apps is a supported recovery method, but it will require reconfiguration of accounts and you should run PowerShell as Administrator.

When should I contact Microsoft or my email provider?

Contact your email provider if the issue appears server-side (outage, auth changes). Contact Microsoft support when the app crashes, Windows updates cause problems, or system file repairs fail to restore functionality.

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In summary, the most common fixes are checking network and account authentication, repairing or resetting the Mail and Calendar app, correcting permissions and time settings, and running system repair tools or updates. If you follow these steps, you should resolve the issue where Calendar doesn’t work in Windows 10 or know when to escalate for support.