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An Unknown Error Occurred on Outlook: Here’s How to Fix It

The methods listed here are confirmed by our experts

7 min. read

Updated onDecember 4, 2023

updated onDecember 4, 2023

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Key notes

An error occurred in an error message that happens for someOutlookusers when sending, receiving, opening, or deleting emails.

That error message more specifically statesAn unknown error has occurred.

The error can include 0x80040119, 0x80040600, 0x80070057, 0x800CCC67 and other codes, and it is usually due to corrupted PST files.

Here are a few tips that might fix theunknown error has occurredissue oran unexpected error has occurredannoying message from Outlook.

How can I fix An unknown error has occurred on Outlook?

1. Run an Anti-Virus Scan

A virus might have corrupted the Outlook data files. That’s more likely if your third-party anti-virus software needs updating.

First, check that youranti-virus softwareis updated; and then run a scan with the utility.

You can usually select a check for updates option within most anti-virus utilities to update the software.

For example, Avast has anUpdateoption on its system tray context menu.

If you don’t already have a third-party utility installed, check out thissoftware guide. Most of the more effective anti-virus utilities also have freeware versions.

Alternatively, you can utilize the Windows Defender app in Windows.

2. Fix Outlook with third-party utility software

There are numerous third-party utility applications with which you can repair Outlook’s PST files. The one that comes highly recommended isStellar Repair for Outlook.

Fixing your PST file is easy. Once you download and install the software, you select the PST file from your computer. Then start the process by clicking theRepairbutton.

The software then provides a preview of the repaired PST file items. Press aSave Repaired Filesbutton on the Home tab to save the scan details.

The software can recover not only emails but calendars, contacts, notes, and attachments. Hence, all that remains to be done is to try the tool for yourself and recover your Outlook benefits right away.

Stellar Repair for Outlook

3. Temporarily switch anti-virus software off

Switching anti-virus software off might be a good fix for unknown errors with the 0x800CCC67 code. In this case, an anti-virus utility might beblocking the SMTP protocol.

Most anti-virus utilities include a disable option on their system tray context menu.

As such, right-click the anti-virus software’s system tray icon and select the disable option to switch the utility off.

Then, try sending an email from Outlook again to see if that fixed the issue.

4. Remove Microsoft Outlook add-ins

Add-ins can generate numerous Outlook errors. As such, removing the add-ins off might also fix unknown Outlook errors. This is how you can remove add-ins from Outlook.

5. Set up a new Outlook Account Profile

Your Outlook profile might be corrupted. In which case, setting up a fresh new account profile in Outlook could feasibly fix the unknown error.

This is how you can set up a new Outlook profile.

6. Fix Corrupted PST Files With the Inbox Repair Tool

Fixing corrupted PST data files is one of the best general fixes for unknown errors in Outlook.

Thus, Outlook includes an Inbox Repair Tool, otherwise, Scanpst.exe, to repair PST files. This is how you can scan a PST with that utility.

7. The Outlook 2010 Hotfix Package

This fix is more specifically for unknown errors with a 0x80070057 code, which usually occurs when you try to set up new profiles with the Auto Account Setup process inMS Outlook 2010.

Microsoft has a hotfix package for the 0x80070057 error. However, don’t expect that hotfix to fix any other unknown error.

You can save that hotfix package to Windows by pressing theHotfix Download Availablebutton onthis website page.

Then, enter an email address to receive an email that includes a download link and password for the hotfix.

Run the hotfix exe, enter the required password, and restart Windows after the hotfix weaves its magic.

Those are some of the best resolutions for Outlook’sunknown error has occurrederror messages.

If further fixes are still required, check out theSupport and Recovery Assistant for Office 365that can also resolve numerousMS Outlookissues.

Start writing the address that shows incorrectly. Press the down arrow key to select an autocomplete addressing delete it. If that doesn’t work, you can follow ourstep by step guide to fix this problem completely.

8. Try a new email client

If you are tired of unknown Outlook errors and corrupted PST files, we recommend switching your email client.

Mailbirdis one of our favorite alternatives to Outlook. Developers are constantly working on it, bringing new features.

You can add multiple email accounts in Mailbird and have a bird’s eye view with the unified inbox. Here’s what else is great about it.

All this is great, but what sets it apart is the free 24/7 support you receive as a client.

⇒Get Mailbird

We have a full list of Outlook errors and the solutions to them in ourOutlook troubleshooting section.

Errors are not the only thing that can happen to Outlook, so if you have any other problems, check ourFix Outlook hubfor answers.

An Unknown Error Occurred on Outlook: Here’s How to Fix It#

How can I fix An unknown error has occurred on Outlook?#

1. Run an Anti-Virus Scan#

2. Fix Outlook with third-party utility software#

Stellar Repair for Outlook#

3. Temporarily switch anti-virus software off#

4. Remove Microsoft Outlook add-ins#

5. Set up a new Outlook Account Profile#

6. Fix Corrupted PST Files With the Inbox Repair Tool#

7. The Outlook 2010 Hotfix Package#

8. Try a new email client#