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Common Outlook Errors and Their Fixes (Step-by-Step)

Follow this Step-by-Step Guide to learn how to fix common Outlook Errors.

Microsoft Outlook is a well-known email client application that is included in your Microsoft 365 subscription and is used all over the world to send and receive email messages. Aside from being an email client, it has a wide range of other features such as the ability to create meetings, appointments, tasks, notes, and much more. However, problems in Microsoft Outlook are almost certain to occur not only because of application failure but also as a result of software malfunction.
When there is a problem with Microsoft Outlook, you’re likely to get a variety of error messages. The following are some of the most common Outlook error messages:

#1 Cannot open your default email folders

You are unable to access your default e-mail folders. There has been an unexpected error. The knowledge service msncon.dll could not be loaded by MAPI. Ensure that the service is properly installed and configured.

The msncon.dll error code indicates an issue with the Outlook Hotmail Connector add-in. As a result, this error message is associated with the Outlook Hotmail Connector. It is a Microsoft software tool that allows you to access and manage your MSN, Live, and Hotmail accounts through Microsoft Outlook. There are two distinct scenarios in which you will encounter this error.

#2 Outlook Connector is no longer installed

Although the Outlook Hotmail Connector does not appear to be installed on your system, you still have an MSN/Hotmail account configured in Microsoft Outlook. You have two choices here:

  • Reinstall the Outlook Hotmail Connector or remove the MSN/Hotmail account from your mail profile if you no longer want to use it.

However, if you already have the most recent version of the Outlook Connector installed on your system and are still receiving this error message, follow these simple steps:

  • First, manually enable the add-in.
  • Now, on your system, install the Outlook Hotmail connecter, then deactivate the Outlook user’s MSN/Hotmail account
  • Relaunch Microsoft Outlook and re-add the MSN/Hotmail account via the Outlook Hotmail connecter menu.
  • Repair the Office installation once the account has been successfully created.
  • Recreate your mail profile once it’s finished.

#3 The connection to Microsoft Exchange Server is unavailable

This is one of the most common Outlook error messages, and you will encounter it quite frequently. The following are the most likely causes of this error:

There is no data connection.

Perhaps there isn’t a data connection available right now. As a result, you should begin by testing your SMTP connection using the Telnet protocol.

Outlook data files have been locked.

It is possible that the Outlook data files, i.e. PST and OST files, are accidentally locked and you are unaware of it. or the Outlook data files have been set to read-only. You should double-check the permissions on those files and ensure that neither is about to become read-only.

Third-party Application Interference

Many third-party applications may interfere with Outlook while it is connected to the Exchange Server. If this is frequently the case, you should start Outlook in safe mode.

#4 Outlook is unable to connect to the proxy server

This error message appears when the Outlook client attempts to connect to a server via an RPC (Remote Procedure Call) or HTTPS (Hypertext Transfer Protocol Secure) connection. The error message is as follows:

“The proxy server’s security certificate could also be a hindrance. The safety certificate does not come from a reputable certifying authority. Outlook cannot connect to the proxy server.”

This Microsoft Outlook error can be caused by several factors, including

  • Attaching to the server requires the use of a certification authority.
  • Perhaps you forgot to put your trust in the certification authority on the basis.
  • The certificate appears to be revoked or revoked.
  • The site’s name does not match the certificate.
  • This error could be caused by a third-party add-in or browser.

There are several items you can try to resolve this Outlook error.

Examine the certificate.

To resolve this issue, you should first examine the certificate and then contact your supervisor. Simply follow these easy steps:

  • In Microsoft Internet Explorer, first, connect to the RPC Server or the secure server. In the address bar, type https://www.server name.com/rpc and hit Enter.
  • Now, in the lower-right corner of the online browser, double-click the padlock icon.
  • Check your knowledge of these two fields by clicking the small print tab:

Valid to

This field specifies the expiration date of the certificate.


Make sure this field matches the name of the location.

Install the trusted root certificate

To install the trusted root certificate, perform the following steps:

  • Click Install Certificate > Next in the Certificate panel.
  • Now, in the following store box, check the Place of all certificates. Then select Browse.
  • Click OK after selecting Trusted Root Certification Authorities.
  • Now, go ahead and click Next > Finish > OK.

Disable the Third-party add-ins

Before you disable any third-party add-in, you should start Outlook in safe mode.

  • To get to the Run prompt, simply press Win + R on your Keyboard.
  • Within the edit box, type Outlook.exe/safe and press Enter.

If Outlook starts normally in safe mode, the important issue is likely related to third-party add-ins. You want to look for and disable third-party COM add-ins here.

  • To begin, open Microsoft Outlook. Click the File tab > Options > Add-ins on the taskbar.
  • Within the Manage box, click COM Add-ins, then click Go.
  • Clear the checkboxes next to the third-party add-ins you want to disable.
  • Restart Microsoft Outlook now.

This article was all about the Most Common Outlook Errors and Their Quick fixes. If you have any questions about this topic, go to Microsoft365.com/setup or office.com/setup.