How to Fix Outlook Error 0x800ccc13

When sending or receiving email in Microsoft Outlook on Windows, you may receive the following error message: “Sending reported error (0x800ccc13): Cannot connect to the network. Verify your network connection or modem.”

This error typically arises immediately after a Windows Update, system migration, or when system integrations with the Windows networking stack become corrupted. It prevents the mail server handshake from completing even when local internet connectivity is fully functional.

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1. What Causes Outlook Error 0x800ccc13?

This error is caused by a communication breakdown between Outlook and the operating system’s networking layer:

• Corrupted System DLLs: System files (specifically mswsock.dll or TCP/IP protocol drivers) are corrupted or damaged, often due to an interrupted Windows Update.
• Conflicts with Third-Party Add-ins: Antivirus email scanners or outdated security plugins lock the outbound sockets.
• Winsock Catalog Mismatch: The Windows network socket configuration has corrupted registry bindings.
• Insufficient Permissions: Outlook is blocked from accessing the network API because it is running in a restricted sandbox or lacks administrative clearance.

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2. Run the System File Checker (SFC) on Windows

Since system file corruption is the most common cause, repairing the core operating system libraries will often fix this error without modifying your mail profile.

Step 1: Open an Elevated Command Prompt

1. Press the Windows Key, type cmd, and right-click Command Prompt.
2. Select Run as administrator.

Step 2: Run SFC and DISM Repairs

Run the following commands in sequence to repair system files and the local Windows component store:

dism /online /cleanup-image /restorehealth
sfc /scannow

[!NOTE] The dism utility retrieves healthy copies of corrupt system components from Windows Update, after which the sfc utility scans and replaces damaged local dll files. Restart your PC after these operations complete.

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3. Perform a Full Office Application Repair

If the system files are healthy but the integration remains broken, trigger a repair of the Microsoft Office suite.

Run Office Click-to-Run Repair

1. Right-click the Start button and select Run (or press Windows Key + R).
2. Paste the following command based on your standard installation to launch the Repair tool:

"C:\Program Files\Common Files\microsoft shared\ClickToRun\OfficeClickToRun.exe" /scenario Repair /platform x64 /culture en-us

3. In the dialog box that appears, select Online Repair (this performs a comprehensive rebuild of all integration keys) and click Repair.

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4. Start Outlook in Safe Mode and Disable Add-ins

Outdated or corrupt COM Add-ins (especially third-party firewalls and antivirus mail scanners) can intercept outbound TCP/IP traffic and drop the sockets.

Step 1: Launch in Safe Mode

Press Windows Key + R, type the following command, and press Enter:

outlook.exe /safe

If Outlook sends and receives mail successfully in Safe Mode, an active add-in is causing the network block.

Step 2: Disable COM Add-ins

1. Click File → Options → Add-ins.
2. At the bottom of the window, select COM Add-ins in the Manage dropdown, then click Go….
3. Clear the checkboxes for all third-party add-ins (especially antivirus, PDF creators, or third-party search tools).
4. Click OK, close Outlook, and restart it normally.

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5. Configure and Reset TCP/IP and Network Sockets

If the system registry holds outdated or corrupted TCP/IP network bindings, reset the network sockets to their default state.

Open Command Prompt as Administrator and execute the following commands:

netsh int ip reset
netsh winsock reset
ipconfig /flushdns

Restart your computer after running these commands to reinitialize the network adapters.

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6. Resolve Communication Issues on macOS

On macOS, this error behaves similarly when Outlook cannot initialize its network background daemons or faces local permission blocks on its cache folders.

Step 1: Force Close Outlook and Reset Network Caches

Run the following terminal commands to close all Outlook processes and flush the local DNS cache:

killall "Microsoft Outlook" 2>/dev/null
killall "Microsoft Outlook Finder Integration" 2>/dev/null
dscacheutil -flushcache
sudo killall -HUP mDNSResponder

Step 2: Verify Port Connectivity

Test if the local machine can establish socket connections with the mail server:

nc -zv smtp.office365.com 587
nc -zv outlook.office365.com 993

If the connection is rejected or timed out, verify that your local macOS firewall or custom VPN is not blocking the respective ports.

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7. Summary Diagnostics Checklist

Diagnostics Step	Action / Path	Expected Outcome
System Integrity	Run dism /online /cleanup-image /restorehealth followed by sfc /scannow	Restores corrupted networking and socket DLLs.
Winsock Reset	Run netsh winsock reset in Administrator Cmd	Rebuilds the network sockets configuration.
Office Repair	Launch Office Click-to-Run Repair utility	Re-registers Office DLLs in the Windows Registry.
Safe Mode Check	Run outlook.exe /safe	Verifies if third-party add-ins are blocking the socket.
macOS Cache Flush	Flush macOS DNS and terminate orphaned processes	Forces macOS to re-establish clean SMTP sockets.