The “Outlook cannot connect to the server” error occurs when the application is unable to establish a connection with the Microsoft Exchange. When this happens, you may fail to send or receive emails, thus impacting your workflow and productivity.
This error can occur due to internet/server connectivity issues or a problem with the Outlook itself or its data file. Let’s discuss the possible reasons behind this error and the methods to fix it.
Reasons behind “Outlook cannot Connect to Server” Error
Outlook may fail to connect to the server due to various reasons, such as:
Network Connectivity Issues: Sloworunstableinternet connectivity can prevent Outlook from connecting to the server.
Server is Down for Maintenance or any other Reason: If the email server is unavailable because of scheduled maintenance or any other reason, Outlook may fail to connect with the server.
Incorrect Internet Protocol Configuration: Incorrect network or Internet Protocol (IP) settings can prevent Outlook from properly communicating with the mail server, causing connectivity issues.
Corrupt or Outdated Cached Authentication Data: Outlook stores authentication information, such as login tokens and credentials, on the computer to avoid requiring you to sign in repeatedly. If this cached data becomes corrupted, expires, or no longer matches your current account credentials, Outlook may fail to authenticate with the mail server, resulting in the errorserrors, like Cannot connect to the server.
Outdated Outlook or Windows: If your Outlook or Windows is not up-to-date, bugs, compatibility issues, or other software problems may affect connectivity with the server.
Damaged MS Office or Outlook Program Files: Damaged Outlook or MS Office program files may prevent it from communicating properly with the server.
Corrupt Outlook Profile: A damaged or corrupt Outlook profile can cause connectivity problems with the server.
Incompatible or Faulty Add-ins: Faulty or incompatible add-ins may interfere with Outlook functionality, causing various issues, including Cannot connect to the server error.
Inconsistent or Damaged OST File: A damaged or inconsistent OST file can cause Outlook to freeze, crash, or even connect to the server.
Methods to Resolve Outlook Cannot Connect to Server
A simple system restart can sometimes resolve minor bugs or glitches in the system that might be causing Outlook to connect to server issue. You can also restart your system and see if it helps. If this doesn’t work, you can follow the methods given to resolve this issue.
Method 1: Check the Internet Connection
A stable network connection is essential for Outlook to communicate with the mail server. If the internet connection is slow, intermittent, or unavailable, Outlook may be unable to synchronize mailbox data or establish a connection with the server.
To check your internet connection, open a web browser and visit any website. If the website does not load, restart your router or contact your Internet Service Provider (ISP). If the internet is working but Outlook still cannot connect, contact your network administrator to check whether the server is down or undergoing maintenance.
Method 2: Update Outlook and Windows
Outdated Outlook application may develop bugs or lead to incompatibility issues that may interfere with its connection to the mail server. Microsoft regularly releases updates that include bug fixes, security improvements, and compatibility fixes. You can check and update Outlook to resolve the issues.
You can also check for available Windows updates and install them. If you are unsure, contact your system administrator for assistance.
Method 3: Disable Faulty Add-ins
Incompatible or faulty add-ins can sometimes interfere with Outlook’s normal operation. You can check whether an add-in is causing the connectivity issue by starting Outlook in Safe Mode. For this, press Windows + R, type outlook.exe /safe in the Run dialog box, and click OK.
In Safe Mode, the application starts without loading the add-ins and custom settings. If your Outlook connects to the server in this mode, it is a clear indication that an add-in is causing the problem. You can disable the add-ins by following these steps:
- Click Add-Ins and then click the Go button besides Manage: COM Add-Ins.
- Uncheck all Add-Ins and then click OK.
- Restart Outlook in normal mode.
If the issue is resolved, activate the add-ins one-at-a-time and check if the connectivity is restored. This will help you find the faulty add-in. When found, remove it permanently.
Method 4: Disable IPv6 Protocol
Some users have reported that they’re able to resolve the connectivity issues between Outlook and the Exchange Server by disabling the IPv6 protocol.
You can also try this workaround to see if helps to fix the issue. Follow the below step-by-step instructions:
- Close Outlook and open the Control Panel. Select Network and Internet.
- In the Network and Internet window, select Network and Sharing Center.
- In the Network and Sharing Center window, choose Change Adapter Settings. This will open the Network Connections window.
- Here, right-click on your connection mode and click Properties.
- Uncheck the Internet Protocol Version 6 (TCM/IPv6) option and click OK.
- Launch Outlook and check if the connection is restored.
Method 5: Reset Cached Authentication Data
Outlook uses cached authentication and identity information to authenticate your account and connect to Microsoft 365 or Exchange services. If this cached data becomes outdated or corrupted, Outlook may fail to authenticate your account correctly, which can cause the Cannot connect to server error.
The OneAuth and IdentityCache folders contain cached authentication and identity information used by Microsoft applications. Removing or renaming these folders forces Outlook to recreate the required authentication data when you sign in again.
You can delete or move these folders to another location. Follow the steps mentioned below:
- Close all Microsoft applications, such as Word, Outlook, Excel, etc.
- Open the Run utility (press Windows + R), type %AppData%, and press Enter.
- In the window that opens, find and open the Microsoft folder.
- Then, move the OneAuth and IdentityCache folders to another location.
- Launch Outlook and sign in to your account.
If the application connects successfully, keep the newly created OneAuth and IdentityCache folders and do not restore the old folders. If the issue persists, close Outlook and restore the original folders from the backup location.
Method 6: Check EnableADAL Registry Key is Enabled
The EnableADAL is a registry key that controls whether Outlook uses the Active Directory Authentication Library (ADAL) for supporting the Modern Authentication (MFA and token-based sign-ins). If this registry key is not enabled (set to ‘0’), then you may face sign in or connectivity problems. You can check if EnableADAL registry key is enabled. Here’s how:
Note: Before doing the changes, back up the registry in case something goes wrong.
- Press Windows + R, type regedit, and press Enter.
- Go to this location:
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity.
- Check the right-hand pane for EnableADAL.
- If it exists, double-click it and ensure the value is set to 1.
- If it is missing, right-click in the right-hand pane and select New > DWORD (32-bit) Value.
- Name it EnableADAL. Double-click it and set the value to 1.
- Close the Registry Editor and start Outlook.
Note: In Outlook 2010, Modern Authentication is not supported. In Outlook 2013, it is not enabled by default, therefore, you need to set the DWORD value of the registry key to 1.
Method 7: Create a New Outlook Profile
A profile contains account information, server settings, and other configuration information that Outlook uses to connect to your mailbox. If the profile gets corrupted, the application may fail to connect to the server. You can create a new Outlook profile to resolve the problem.
Method 8: Repair or Reinstall Microsoft Office
Damaged or corrupted Microsoft Office program files can cause Outlook to freeze, crash, or fail to connect to the server properly. You can repair the Office application to fix the problem. After repairing, restart your system and see if the error is resolved. If it persists, then you can uninstall and reinstall the Microsoft Office.
Method 9: Rebuild or Recreate the OST File
A corrupt or inconsistent OST file can interfere with Outlook’s ability to synchronize the locally cached mailbox data with the server. In such a case, you can recreate the OST file after taking its backup.
Once the file is recreated, check if there are any missing mailbox items. If there are any missing items, you can recover the items from the backup OST file using Stellar Converter for OST. This powerful OST to PST converter tool can help you recover missing mailbox items from the backup OST file and save them in a PST file with integrity and precision. You can then import this PST file into your Outlook profile to restore it. You can also use this tool to export the converted PST directly to an existing Outlook profile, Microsoft 365 account, or Exchange Server.
How to Fix “Outlook cannot Connect to Server” Error in New Outlook?
If you are using New Outlook, then you can try the following methods to troubleshoot this issue:
- Make sure your device has a stable internet connection.
- Sign out of your account in New Outlook and then sign in again. This can refresh your authentication session and resolve problems caused by expired or invalid sign-in tokens.
- If the account configuration is causing the problem, remove the affected account from New Outlook and add it again. This allows Outlook to establish a fresh connection with the mail server.
- If the problem affects only your work account, the issue may be related to your organization’s account, authentication policy, Exchange configuration, or service availability. In that case, contact your IT administrator for further investigation.
Conclusion
Outlook cannot connect to the server error may occur due to various factors mentioned in this post. You can follow the methods to fix the error. If the issue occurs due to a damaged OST file, take a backup of the file and then delete it. This will create a new OST file. However, if you find missing items in your new OST file, then you can retrieve the items from the backup OST file using Stellar Converter for OST and save them in a PST file. You can then import this PST into your Outlook profile.
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