Fix Windows 10 Mail Sync Error 0x86000c0a

Windows 10 Mail sync error 0x86000c0a usually appears when the Mail app cannot connect to your email server, often due to a corrupted cache, an outdated app, or an incorrect password. The most reliable fix is to clear the Mail app’s cache and re-enter your account credentials; if that fails, updating the app or removing and re-adding the account usually resolves it.

What Causes Error 0x86000c0a?

This error is part of the 0x86000xxx range, which the Windows 10 Mail app uses to indicate sync or authentication problems. The specific code 0x86000c0a typically points to a failure in the sync process itself, not a network outage. Common triggers include:

• Stale cached data – The app stores a local copy of your mailbox; if it becomes corrupted, sync fails.
• Outdated Mail app – Older versions may have bugs that newer updates fix.
• Incorrect password or authentication change – If you changed your email password or your provider enabled two-factor authentication, the app may not have the new credentials.
• Server-side issues – Sometimes the email provider (Outlook.com, Gmail, Yahoo, etc.) is temporarily down or requires re-authentication.
• Date and time misconfiguration – If your PC’s clock is off, SSL/TLS connections can fail, causing sync errors.

Before You Start: Quick Checks

Try these simple checks first; they take less than a minute and often solve the issue:

1. Check your internet connection – Open a website in your browser. If it doesn’t load, fix your network first.
2. Verify your email password – Log in to your email provider’s webmail with the same credentials you use in the Mail app. If you can’t log in there, the problem is with your account, not the app.
3. Check the date and time – Right-click the clock in the taskbar, select Adjust date/time, and ensure Set time automatically is on. If it’s off, turn it on and sync.
4. Restart the Mail app – Close it completely (right-click the icon in the taskbar and choose Close window) and reopen it.

Fix 1: Clear the Mail App Cache

The most common fix for error 0x86000c0a is clearing the app’s cache. This does not delete your emails – they are stored on the server – but it removes the local copy that may be corrupted.

1. Open Settings (Windows key + I).
2. Go to Apps > Apps & features.
3. Find Mail and Calendar in the list. (It may appear as two entries; use the one that says “Mail and Calendar�.)
4. Click on it, then select Advanced options.
5. Scroll down and click Reset. This clears the app’s data and cache.
6. Reopen the Mail app. You will need to add your accounts again.

If you prefer not to reset (which removes all your configured accounts), you can try a less invasive cache clear: press Windows key + R, type wsreset.exe and press Enter. This resets the Windows Store cache, which sometimes helps.

Fix 2: Update the Mail App

Microsoft regularly updates the Mail and Calendar app to fix bugs. An outdated version may have a known issue with sync that is already patched.

1. Open the Microsoft Store.
2. Click the Library icon (bottom-left).
3. Click Get updates.
4. Wait for the update to finish, then restart your PC and try Mail again.

Fix 3: Remove and Re-add Your Email Account

If clearing the cache didn’t help, the account configuration may be corrupted. Removing and re-adding the account forces the app to re-authenticate and re-sync from scratch.

1. Open the Mail app.
2. Click the gear icon (Settings) at the bottom-left.
3. Select Manage accounts.
4. Click on the account that is showing the error.
5. Choose Delete account and confirm.
6. Close the Mail app and reopen it.
7. Go back to Settings > Manage accounts > Add account.
8. Select your email provider (Outlook.com, Google, etc.), enter your email and password, and follow the prompts.

If your provider uses two-factor authentication, you may need to generate an app-specific password instead of your regular password. Check your provider’s help page for instructions.

Fix 4: Check for Windows Updates

Windows 10 itself may have a bug that affects the Mail app. Installing the latest updates can resolve underlying issues.

1. Open Settings > Update & Security > Windows Update.
2. Click Check for updates.
3. Install any pending updates and restart your PC.

Fix 5: Re-register the Mail App (PowerShell)

If none of the above works, you can re-register the Mail app using PowerShell. This is a more advanced fix but is safe and does not delete your data.

1. Right-click the Start button and select Windows PowerShell (Admin).
2. Copy and paste the following command, then press Enter:

Get-AppxPackage Microsoft.windowscommunicationsapps | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}

3. Wait for the command to finish (it may take a minute).
4. Close PowerShell and restart your PC.

This re-registers the app with Windows, which can fix deeper corruption.

Frequently Asked Questions

Will I lose my emails if I reset the Mail app?

No. Your emails are stored on your email provider’s server. Resetting the app only clears the local cache and your account settings. You will need to re-add your accounts, but your emails will re-download.

Why does it happen only with one account?

If only one account fails, the problem is likely with that account’s credentials or server settings. Check the password and ensure your provider isn’t having an outage. You can also try removing and re-adding just that account.

Does this error affect Outlook desktop or Outlook on the web?

No, this error is specific to the Windows 10 Mail app. If you use the full Outlook desktop client or Outlook on the web, they use different sync mechanisms and are not affected.

Can I use a third-party email client instead?

Yes. If the Mail app continues to fail, you can use Outlook (the desktop version), Thunderbird, or webmail. However, the fixes above usually resolve the issue, so it’s worth trying them first.

What if none of these fixes work?

If the error persists after all these steps, the issue may be on your email provider’s side. Check their status page or contact their support. You can also try creating a new Windows user account and setting up Mail there – if it works, the problem is with your user profile.

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