How to Fix Outlook Will Not Connect to Office 365 Issue?

Microsoft Outlook is an integrated Microsoft 365 app for emailing and sharing information. It is one of the most popular and widely used email clients by various large organizations and enterprises. Moreover, it provides access to various productivity tools such as calendars, contacts, and more. Though Outlook is a secure and safe platform for sending and receiving emails, it is not immune to some occasional errors. One such error is ‘Outlook will not connect to Office 365.’

Reasons for ‘Cannot Connect Outlook to Office 365’ Issue

Mentioned here are some of the reasons for causing Outlook connectivity errors:

• Login via incorrect credentials.
• Disrupted internet connection
• Improper Outlook installation
• Corrupt or Damaged OST (Outlook data files)
• OST synchronization errors
• Corrupt Outlook profile
• Incompatible add-ins
• Disabled mailbox from the Exchange server
• Firewall and Antivirus settings.

Any of these can cause ‘Outlook cannot connect to online Microsoft 365.’

Enable Troubleshooting Outlook

The fastest way to find the cause of Outlook connectivity problems is to use Outlook’s built-in troubleshooting feature. Follow the procedure mentioned below to start troubleshooting:

• Launch the MS Outlook program.
• Go to File and then to the Options.
• The Outlook Options wizard opens. Click on the Advanced tab.
• In the Others section, check the Enable Troubleshooting logging option.

• After that, click on OK and restart your PC.

This process will help you find the actual cause of the error but cannot solve it. You can diagnose the real cause and apply the corresponding method for that. Therefore, here are solutions to fix this issue.

Ways to Resolve Outlook Will Not Connect to Office 365

In this section, we will discuss various ways to fix the Outlook connectivity issue with Office 365. Do as instructed below.

#1: Ensure Proper Internet Connection and Restart System

The most basic cause for this issue may be improper internet connectivity. As soon as you run your PC, many applications start running in the background. Thus, this may interrupt the procedure of connecting Outlook to Office 365. Therefore, it is important to make sure you have a proper internet connection and then restart the system. After that, refresh your system before connecting Outlook to M365.

Sometimes, just rebooting your system can fix many errors. However, if you still face Outlook cannot connect to Microsoft 365 error, move to the other procedure.

#2: Turn Off the Work Offline Mode

Firstly, check whether the Work Offline Mode feature of Outlook is disabled or not. If this feature is enabled, it prevents you from performing any actions that demand a connection to the server. So, follow the steps below to disable Work offline mode:

1. Open MS Outlook.
2. Go to the Send/Receive tab.
3. Click on the Work Offline option to disable it.

Now, your Offline mode is turned off. If the problem persists, try another method to fix Outlook cannot connect to online Microsoft 365.

#3: Disable Faulty Add-Ins

Outlook allows users to install Add-Ins to enhance and extend the functionalities of the application. However, sometimes installation of these Add-ins may cause errors in the functioning of the application. So, users might take steps to deactivate them. Follow the steps as instructed:

• First, run Outlook in safe mode. For that, press the Window+R key, and type “outlook.exe /safe”. Click OK.

If MS Outlook connects to Office 365 after running it in Safe Mode, it verifies that the add-in is causing the error. Therefore, we will uninstall the necessary add-ins from the application.

• Close running Outlook. Re-launch the app in standard mode instead of safe mode.
• Once Outlook is open in Standard mode, open the File tab. Click on Options.
• Outlook Options window opens. Select COM-Add-ins in the Manage section. Click on the Go button.

• Here, de-select all add-ins, and select them one by one, and click OK. This will help you keep a note of the defaulter add-in.

• Once you find the one causing the issue, remove it.

Again, if Outlook will not connect to Office 365 error is not resolved, try Troubleshooting Exchange Server Connection.

#4: Repair, Upgrade, And Re-Install the Latest Office 365 Version

The Outlook connectivity issue can also be caused due to corrupt Outlook or Office 365 application files. This can be fixed either by repairing or reinstalling the application. Do as directed below.

Repair MS Office Installation

• Go to the Start and launch Control Panel.
• In the Programs, click on Program and Features.
• Then, select the Microsoft Office application from the list and click on Change.

• Out of the given options, select Repair and tap Continue.

After this, open MS Office 365 and check if Outlook cannot connect to Microsoft 365 issue is resolved. If not, you need to Re-install MS Office.

Uninstall and Reinstall Office 365

1. Download the Microsoft Support and Recovery Assistant tool.
2. Launch Office 365 and delete it using the Microsoft Support tool.
3. Follow the setup prompts: Click on Install > I Agree.
4. Tick the Office 365 version you need to remove. Click Next.
5. Restart your PC after removing Office 365.
6. Use the included MS Office Uninstall Wizard to completely remove Office from your system.
7. The program will reopen automatically to finish the removal process.
8. Choose the desired version of Microsoft Office that you want to install.
9. Follow the setup instructions to complete the reinstallation of Microsoft Office.

#5: Use the SSL/TLS Encryption

Follow the steps below to set SSL/TLS type encryption:

1. Open Outlook.
2. Click on File and then go to Account Settings.
3. Further, from the drop-down menu, click on Server Settings.
4. In the Encryption method, choose SSL/TLS.
5. Tap on Next.

Another effective method to resolve Outlook will not connect to Office 365 is to restore corrupt Outlook Data Files (OST or PST).

#6: Restore Corrupt or Damaged Outlook Data Files

If your Outlook data files get corrupted or damaged, it may cause a “Cannot connect Outlook to Office 365” error. However, we have a solution to restore Outlook data files to Outlook and solve the error. Follow the steps to Repair Corrupted PST File using Scanpst.exe:

1. First, open File Explorer.
2. Go to the C:\.
3. Select Program Files(x86).
4. Type SCANPST in the search box.
5. Double-click on the scanpst.exe to run the application.
6. Click on Browse to specify the Outlook data file.
7. Click on the Start button.

This Outlook repair tool (Scanpst.exe) will scan the damaged PST files and repair complete data. Re-start the Microsoft Outlook application. Also, you can use the DRS PST Recovery Tool to recover corrupt or damaged PST files. Apart from this, there can be other reasons causing this connectivity issue such as Firewall and Antivirus settings and others.

Once the PST file is repaired and restored check if Outlook connects to Office 365. If not, here is an instant solution to access Office 365 mailbox data without Outlook connectivity.

#7: Professional Solution When Outlook Will Not Connect to Office 365

Let’s say you’re trying to access an Office 365 account or another Exchange Server account using Outlook, but fail to do so. In that case, you can use the DRS Office 365 Email Backup Tool to save Office 365 data locally and access it anytime. However, this tool does not allow you to directly access the Office 365 mailbox in MS Outlook. But, you can access Office 365 mailbox in another way. This tool enables users to back up Office 365 mailboxes to various file formats and email clients. So, you can easily download the data in PST, MBOX, EML, CSV, or PDF for quick access. Besides, there are other advanced features of the tool that will enhance your user experience.

Conclusion

We have researched and shared various tasks when Outlook will not connect to Office 365. Well, knowing the cause of the error makes it easier to choose the appropriate solution. Therefore, before adopting any of the methods mentioned above, try to find out the main reason for such an error. Still, if none works, the professional tool will help you view Office 365 mailbox data without any hassle.