How To Fix Outlook Not Connecting to Office 365?

Updated On - December 18, 2023 by Nasir Khan | Reading Time: 5 minutes

Outlook is a widely used email client that provides seamless communication and productivity features. However, sometimes users may encounter issues with Outlook not connecting to Office 365, which can disrupt workflow and cause frustration. In this blog post, we will explore the common causes behind this problem and provide effective solutions to fix it.

You’re not alone if you’re having trouble connecting Outlook to Office 365. Many users have reported this issue, and it can be frustrating. Luckily, you can try a few things to get Outlook up and running again.

What causes Outlook not connecting to Office 365?

Several factors can contribute to Outlook not connecting to Office 365. It’s essential to understand these causes before implementing the solutions. Here are some common reasons:

  • A faulty internet connection
  • Incorrect DNS settings
  • The Office 365 server is down
  • Your administrator has disabled your account
  • You are not using the correct Office 365 email address or password

How to fix Outlook not connecting to Office 365?

If you encounter, the error message “Outlook cannot connect to Office 365,” try one of the solutions listed below. Any version of Outlook from 2007 to 2019 can use these techniques. You should always make a copy of your OST files before beginning any new method. That way, you can rest easy knowing that you have a copy of your data stored safely away, just in case something unforeseen happens.

Now, let’s delve into the solutions to resolve the issue of Outlook not connecting to Office 365.

Method1: Make Sure That You Are Connected to The Internet and Restart Your Computer

The first step is to ensure that your computer has a stable internet connection. If there are any connectivity issues, try restarting your router or connecting to a different network. Additionally, restart your computer to refresh the system and network settings.

Outlook cannot establish an Internet connection if there is a momentary problem with any of the many processes operating in the background every time you use a PC.

A simple reboot may do wonders for a computer. It terminates all running programs and resolves several associated issues.

If you still get the same error message and Outlook can’t establish a connection to the server, try the following method.

Method 2: Disable Add-Ins 

Sometimes, incompatible or misbehaving add-ins can interfere with Outlook’s connection to Office 365. Unreliable or incompatible add-ins could prevent the Outlook from establishing a connection with the Exchange server. It is possible that a malfunctioning plugin is to blame for the error, to check if add-ins are causing the problem, follow these steps:

  • Press the Windows key plus R, type Outlook /safe, and finally, press the Enter key or click “OK” to launch Outlook in safe mode.


  • Next, click on File tab and choose the Options.


  • Select “Add-Ins,” and then hit the “Go” button.


  • Uncheck the Add-ins checkbox and hit “OK.”


  • At last, launch Outlook in Normal mode once more.

Start activating add-ons one by one and make a note of the Outlook error until the problem disappears. This will help you identify problematic plugins so you can disable them.

Open Outlook and see if the problem resolve; if not, move on to the next solution.

Method 3: Update to the latest Outlook version

Using an outdated version of Outlook can lead to compatibility issues with Office 365. To ensure smooth connectivity, follow these steps to update Outlook:

  • Select ‘File’ in Outlook’s menu bar’s upper left-hand corner.


  • Select “Office Account” from the menu bar.


  • In the right pane, under the heading ‘Office Updates,’ select Update Options, and then click Update Now.


If the “Outlook cannot connect to office 365” error persists after you’ve applied the latest Update, you’ll know it’s time to attempt a different approach.

Method 4: Reinstall Microsoft Office on Your Computer 

Corrupt or damaged Outlook or Office application files are another common sources of connectivity problems. To resolve this issue, repair or reinstall Microsoft Office.

This is how you fix Microsoft Office if it has already been installed on your computer:

  • Go to control panel and select Uninstall an application.


  • Select Microsoft Office, and then hit “Change.”


  • Hit the “Repair” and “Continue” buttons to fix Microsoft Office.


Launch Microsoft Outlook immediately. Reinstalling Microsoft Office is another option if this does not fix Outlook’s inability to establish a connection to the server.

Here’s how to remove Microsoft Office and reinstall it:

  • After downloading the support tool, launch Office and delete it.


  • The next thing to do is click the “Install” button.
    • Following the setup, you can access Microsoft Support and Recovery Assistant.


  • Click “I Agree.”


  • Select the version of Office you wish to remove and Click “Next”.


  • Restart your computer and then use the included MS Office Uninstall Wizard to remove Office from your computer altogether.
  • The programme will reopen on its own to finish the removal.
  • Pick the MS Office version you want to install and carry on with the setup.

Method5, Recreate or Rebuild OST files

If none of the above methods resolves the issue, you can attempt rebuilding the OST file that contains your Outlook data. The existing OST file can be replaced by a new one, relocated, or renamed to achieve this.

C:UsersUsernameAppDataLocalMicrosoftOutlookost.ost is the typical location for the OST file.

However, the OST file’s location can change from one version of Outlook to another. To learn more, read our tutorial on where to look for the OST file.

Other Fixes

Resetting your computer is the best way to get rid of most issues. One option is to make a copy and save it. The “Outlook cannot connecting to Office 365” error can be remedied by the methods described below.

  1. Start Windows Update: If you are using an outdated version of either the Outlook client or Windows itself, you may encounter problems sending and receiving emails. Windows Update can help you get the most recent versions of Outlook and the other Microsoft 365 desktop apps.
  2. Do a Microsoft 365 Health Check: Microsoft’s diagnostic tools might help you determine what’s causing your network problems. Diagnostics perform automatic checks to identify issues and recommend courses of action. Select Run Tests: Outlook User Connectivity to download and execute the diagnostic. For this function, you’ll need a Microsoft 365 administrator’s login.
  3. Modify Your Outlook Information: Open Outlook for Windows to make changes to your account. To access your personal information, go to the File menu, sign in to your Office account, go to the User Information tab, and click About Me. Clicking this link will open your Office 365 profile in a new tab or window in your browser. To make changes to your profile, you can now do so.You can also update your profile through Outlook on the Web (OWA) by going to Profile image, My profile, and Update profile.

Fix Outlook PST files and import them into Office 365 using professional tool

If none of the above methods work, a corrupted Outlook PST file might be causing the connection problem. To fix this, you can use a reliable PST repair tool like Regain PST Repair Tool. Here’s how:

  • Download and install Regain PST Repair Tool on your computer.
  • Launch the software and select the corrupted PST file.
  • Choose the repair option to initiate the scanning process.
  • After the repair is complete, preview the recovered data.
  • Click on the “Save” button to restore the repaired PST file.
  • In the next wizard, browse location to save PST file or you can directly import into Office 365.

Once the PST file is repaired, open Outlook and check if it connects to Office 365 without any issues. Regain Outlook PST recovery tool is specially coded for this task and is recommended by several professionals. You can get more about this solution for free from here.

Free Download100% Secure Buy NowPrice: $39


Outlook not connecting to Office 365 can be a frustrating experience, but by following the methods outlined in this blog, you can effectively resolve the problem. Remember to check your internet connection, disable add-ins, update Outlook to the latest version, and use a reliable PST repair tool if necessary. With these steps, you can regain seamless access to your Office 365 account through Outlook and resume your productive workflow.

Author: Nasir Khan

I am Nasir Khan from India, working as a Content Developer in Regain Software. Here I am writing about our products and their updates. And writing some free solutions from converting emails or Cloud Migration process. We have tools like Email Converter, Emails backup and Cloud migration.

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