How to Fix the Outlook Not Connecting to Office 365 Issue?

How to Fix the Outlook Not Connecting to Office 365 Issue

Microsoft Outlook, a popular email client, can be configured with Microsoft 365 (Office 365) or Exchange Server account. Sometimes, you’re unable to send or receive emails as Outlook fails to connect with Office 365. This usually happens if there are network connection issues. However, the issue may also occur due to various other reasons. In this article, we will discuss the possible causes of the Outlook not connecting to Office 365 issue and see how to fix this issue.

Causes of Outlook not Connecting to Office 365 Issue

Here are some possible causes of the Outlook not connecting to Office 365 issue:

  • Incorrect username/password
  • Damaged or corrupted OST files
  • Internet connectivity issues
  • Corrupted Outlook profile
  • Incompatible Outlook add-ins

Solutions to Fix the Outlook not Connecting to Office 365 Issue

As a first step, you can check if your internet is stable and working properly. You can try to open any random website on your system to see if internet is working. You can also try to connect another device to ensure that it is working fine. If internet is working fine, then follow the below solutions to resolve the issue.

Solution #1: Update Windows and Outlook

Sometimes, outdated versions of your Outlook or Windows operating system can cause incompatibility issues. Check if Outlook application and Windows OS have the latest updates installed.

To check and update your Outlook, follow these steps:

  • Open Outlook and navigate to File.
  • In the left-hand pane, look for “Office Account” and click it.
  • Next, click Update > Update Now.
  • Wait for the updates to install. Then, restart Outlook.

To update Windows,

  • Look for notifications on your system tray and simply click them for the updates to get installed.
  • Alternatively, type “Windows Update” in Windows Search box and click on Windows Update.
  • Then, check for any pending updates and install them.
  • Once the updates are installed, the system will prompt you for a restart. Restart it.

If the issue still exists, move to the next method.

Solution #2: Disable Add-Ins

Sometimes, incompatible or faulty third-party Outlook add-ins can cause issues, like Outlook not connecting to Office 365. You can identify the faulty add-ins and disable them to resolve the issue.

To check if any add-ins are causing the issue, start Outlook in safe mode. To do so, open the Run dialog box (press Windows + R) and type “outlook /safe.” Press OK.

If, in safe mode, Outlook works without any issue, it indicates add-ins were causing the issue. You can disable the add-ins by following these steps:

  • Navigate to File > Options > Add-ins. Click the Go button.
  • Uncheck all the add-ins and click OK.

Now, start Outlook normally and enable one add-in at a time to identify the faulty one. When found, remove it permanently to fix the issue.

Solution #3: Repair/Reinstall Microsoft Office

Sometimes, MS Office installation files get corrupted/damaged, preventing Outlook from connecting to Office 365. You can repair MS Office to resolve the issue. Follow the below steps.

  • Go to the Control Panel > Programs > Uninstall programs.
  • Select Microsoft Office and click Change.
  • In the dialog box that opens, select “Repair”.
  • Follow the instructions to complete the repair process.

If this doesn’t work, uninstall and reinstall the MS Office program. The easiest way to do this is through Microsoft Support and Recovery Assistant. Download this tool and install it.

Open the tool and select the Office version you want to uninstall. This tool will automatically uninstall Office and restart the system. Then, the tool will prompt you to select a version to install. Follow the instructions to install the program.

Solution #4: Rebuild the OST Files

Corrupt or damaged Outlook data file (OST) can also prevent Outlook from connecting to Office 365. In such a case, you can recreate or rebuild your OST file. Close Outlook and go to the OST file location. It is located in the C:\Users\UserName\AppDataLocal\Microsoft\Outlook\ folder. Move the OST file to another location to create its backup. Now, start Outlook. It will create a new OST file and synchronize mailbox items from the server.

When the synchronization is finished, check for any missing emails and other items. If you found any missing items, then use a reliable third-party OST to PST converter tool, like Stellar Converter for OST. It helps you to extract missing items from the backup OST file and save them in a PST file. You can then import this PST file into your Outlook account to access the missing items.

Final Thoughts

If Outlook is not connecting to Office 365, you’re not able to send and receive the emails. There are several reasons, such as no internet connectivity, corrupted OST file, faulty add-ins, etc. that can prevent Outlook from connecting to Office 365. You can try the solutions mentioned in this article to resolve the issue.