How to fix
0x800CCE05 Outlook error
on Windows

Hi, I've been trying to send out emails as per usual in Outlook, and they just keep failing with an error code 0x800CCE05 - it is saying "Unknown error." How do I fix this?

Microsoft Outlook is a staple tool in most businesses and personal life, offering a comprehensive suite of features for email management, calendaring, task tracking, and contact organization. With a clean and intuitive interface, it streamlines communication and enhances productivity for millions of users worldwide. As a sophisticated piece of software, Outlook consolidates numerous functions, making our lives easier. However, no software is impervious to issues, and occasionally users might encounter errors.

One such error that some Outlook users may experience is the 0x800CCE05 error. This typically occurs when attempting to send or receive emails, which can significantly disrupt daily communication and workflow. This error code is usually associated with the Windows system itself rather than being a standalone problem within Outlook.

The error 0x800CCE05 often arises due to improper configuration of the system or network settings. Factors like an unstable internet connection, incorrect SMTP/POP settings, or even firewall and antivirus settings blocking Outlook could lead to this error. Another probable cause could be the corruption or damage of the PST (Personal Storage Table) file, which stores all the Outlook data. Moreover, sometimes, corrupted or outdated system files can also trigger this error.

Dealing with such an error may be challenging for users without technical knowledge, but worry not. A comprehensive guide on resolving this issue can be found below this article, where we walk you through various solutions step by step, starting from basic troubleshooting to more complex approaches.

Another helpful resource to consider is the [d1] PC repair tool. This software doesn't directly address the 0x800CCE05 error, but it is capable of fixing corrupted system files, resolving registry issues, and cleaning junk that might indirectly contribute to this problem.

Fix 1. Check your internet connection

This is a straightforward yet crucial step. A stable and robust internet connection is necessary for Outlook to function correctly. If your connection is intermittent or weak, it could be the reason for the 0x800CCE05 error. Running network troubleshooter could address this issue:

• Right-click on Start and pick Settings.
• Go to Network & Internet section.
• On the right side, find the Advanced network settings section.
• Click Network troubleshooter, specify the problem, and wait till the scan is finished.
• When done, apply all the recommendations.

Fix 2. Repair Office suite

• Type Control Panel in Windows search and press Enter.
• Select Programs > Programs and Features.
• Select Microsoft Office and click on Change.
• Choose the option for Online Repair and click Repair.
• Follow the prompts to finish the process.

Fix 3. Repair the PST file

Corruption in the PST file could result in errors in Outlook. The in-built "inbox repair tool" (SCANPST.EXE) can fix these issues.

• The Office suite, including Outlook, is usually installed in the Program Files folder on your computer's system drive, such as C:\Program Files (x86)\Microsoft Office\Office version or C:\Program Files\Microsoft Office\Office version- go to this location.
• Double-click on SCANPST.EXE to launch it.
• Click on the "Browse" button to navigate to the location of your PST file. By default, this should be in Documents\Outlook Files. If not, you may need to search your system for ".pst" files.
• Once you've selected the PST file, click "Start" to begin the scanning process. This may take some time, depending on the size of your PST file.
• If the tool finds errors in your PST file, you will be prompted to start the repair process. Click on "Repair."

Fix 4. Run SFC and DISM

System File Checker is a utility in Windows that allows users to scan for corruptions in Windows system files and restore them.

• Type cmd in Windows search.
• Right-click on Command Prompt and select Run as administrator.
• User Account Control will ask whether you want to make changes - click Yes.
• Use the following command lines, pressing Enter each time:
  sfc /scannow
• After the scan is done, copy the following commands and press Enter:
  DISM /Online /Cleanup-Image /CheckHealth
  DISM /Online /Cleanup-Image /ScanHealth
  DISM /Online /Cleanup-Image /RestoreHealth
• Restart your device.

Fix 5. Disable Antivirus and Firewall temporarily

Third-party antivirus software and firewalls aim to protect your system from external threats. However, in certain instances, they might overextend their protective measures and inadvertently interfere with legitimate applications like Microsoft Outlook. They might misidentify the network activity from Outlook as suspicious and block its access to the internet.

This blocking can prevent Outlook from communicating with the email server, leading to errors like 0x800CCE05 when trying to send or receive emails. Therefore, temporarily disabling your third-party antivirus or firewall can be an effective solution.

By doing so, you're essentially giving Outlook an unimpeded path to connect with the email server. If the error is resolved after disabling these, you might need to add Outlook as an exception in your firewall or antivirus settings to prevent the issue from recurring in the future. 

Fix 6. Reinstall Office

• Right-click on Start and pick Apps and Features.
• Scroll down to find the MS Office installation.
• Click Uninstall and confirm with Uninstall.
• Follow on-screen instructions to remove the app completely.
• Press Win + E to open File Explorer.
• Navigate to the following location and delete its contents:
  C:\Program Files\Microsoft Office
• Next, type regedit in Windows search and press Enter.
• Go to the following locations in the Registry Editor and delete these items:
  Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\AppVISV
  Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun
  Computer\HKEY_CURRENT_USER\Software\Microsoft\Office
• Reboot the PC and then reinstall Microsoft Office.