Repair PST File

How to fix New Outlook crashing with ERROR CODE 401

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    Summary: The error code 401 occurs when Outlook user enters the wrong credentials for login. This comprehensive guide explains the reasons for the ERROR CODE 401 in the new Outlook for Windows and provide stepwise instructions to troubleshoot and fix the issue effectively. It also mentions an advanced PST repair tool that can help fix the error if corruption in the PST file is the cause behind the error.

    The error code 401 often appears when an Outlook user launches the application followed by an Outlook crash or the app becoming unresponsive. This error indicates unauthorized access where either the credentials (username and password) are wrong or the way the credentials are stored by Outlook or sent to the mail server has some issue. This Outlook crashing error can significantly impact productivity and disrupt daily communication. In this guide, we will be discussing the reasons behind this Outlook error and see how to resolve it.

    Reasons behind the ERROR CODE 401

    The error code 401 may appear in the new Outlook for Windows due to one or more of the following reasons:

    1. Incorrect or expired password
    2. Two-factor authentication
    3. Network issues
    4. Server downtime
    5. Lack of account permissions
    6. Issues with the Outlook client or post-update glitches
    7. Corrupt Outlook profile
    8. Damaged or corrupt Outlook data file (PST)
    9. Conflicting or incompatible third-party add-ins
    10. Outdated Outlook application

    Solutions to Troubleshoot and Fix the Error 401 in Outlook

    To resolve the Outlook crash error code 401, follow these solutions in the given order.

    1. Check and Update Password

    First, ensure that the password you’re using to log in to email in Outlook is correct. In case the password has been changed recently by you or the administrator, make sure to update it in Outlook.

    If you think the password you are entering is correct but Outlook is still crashing with the error code 401, try to log in to the Outlook web. This will help verify if the password is correct. This will also help check the server status – whether it’s online or offline. You can also reach out to your administrator to reset the password. 

    2. Use App-Specific Password

    If your organization has recently enabled or enforced two-factor or multi-factor authentication for account security, then your regular password may not work in Outlook. In such cases, you need to generate an app-specific password and then use this password to log in to Outlook.

    To know how to generate app-specific passwords, you can refer to the email service provider’s website or documentation. You can also reach out to them or your email administrator for help. Alternatively, you can disable two-factor authentication. However, this may compromise your account security.

    3. Check Internet and Network Connection

    Sometimes, temporary issues or glitches with the network connection may also disrupt Outlook functions, leading to the error code 401. In such a case, you can:

    1. Ensure your internet connection is stable
    2. Make sure no VPN is running in the system
    3. Disable the firewall temporarily to ensure Outlook’s access to the mail server is not blocked
    4. Contact the service provider to fix the issues with the internet and then try launching Outlook

    4. Close and Restart Outlook

    If Outlook is crashing with the error code 401, you can try to close Outlook and all its processes via Task Manager and then start Outlook. Alternatively, you can also try to restart the system and then launch Outlook. Sometimes, these basic troubleshooting steps can help fix temporary glitches with the system or application and resolve errors, such as error code 401.

    5. Repair or Reinstall Outlook

    Problems with the Outlook client, such as damaged or missing program files or other critical files can lead to issues, like Outlook crashing. By repairing Microsoft Office (Outlook is a part of the MS Office suite), you may fix the error code 401 and prevent Outlook from crashing. The steps to repair Outlook are as follows:

    1. Close Outlook and navigate to Control Panel > Programs and Features.
    2. Select Microsoft Office (or Outlook) from the list and click Change.
    Select Microsoft Office or Outlook app from control panel
    • You will see repair options, such as Quick Repair and Online Repair. Choose the Quick Repair method and then click Repair
    • If the error persists, choose the Online Repair option and then complete the repair process by following the wizard.

    After the repair, restart the system and then launch Outlook.

    6. Find and Remove Faulty Third-Party Add-ins

    You can launch Outlook in safe mode to check if any faulty add-ins are causing the error. In safe mode, Outlook runs with essential services and does not allow add-ins to run. If Outlook functions properly in safe, then find and remove the faulty add-ins. The steps are as follows:

    1. Close Outlook and press the Windows key + R.
    2. In the Run dialog box, type outlook.exe /safe and press the Enter key to start Outlook in safe mode.
    3. Then, click File > Options and select Add-ins. 
    4. Click the Go… button and then in the COM-Add-ins dialog box, unselect all the add-ins.
    5. Click OK to disable all the add-ins.
    Click OK to disable all the add ins.
    1. Once the add-ins are disabled, restart Outlook normally.

    If Outlook runs smoothly and does not crash or display the error code 401, then do the following:

    1. Enable one add-in at a time
    2. Restart Outlook and then observe if Outlook crashes and shows the error code 401.
    3. Repeat enabling all add-ins one-by-one followed by Outlook relaunch.
    4. As soon as the error reappears, remove the previously activated add-in from Outlook to permanently fix the Outlook crashing issue. 

    7. Create New Outlook Profile

    A damaged or corrupt Outlook profile may also lead to the error code 401. However, you can create a new profile to resolve this issue. The steps are as follows:

    1. Go to Control Panel > Mail > Show Profiles.
    2. Then, click Add. Enter a name for this profile and click OK
    Then click Add. Enter a name for this profile and click OK
    • Log in and set up your same email in the account setup wizard under this new profile.
    • Once the account setup is complete, make this profile default and then launch Outlook. 
    Once the account setup is complete make this profile default and then launch Outlook

    If the corrupt profile was the reason behind the error code 401 and Outlook crash, the error should be resolved now and everything should work well now.

    8: Repair the PST File

    Sometimes, the problem lies with the Outlook data file, such as PST that contains all the mail items, including your credentials. When this file gets damaged or corrupt, you may encounter various issues in Outlook, including Outlook crash. Therefore, you must try to repair your PST file to fix the errors and inconsistencies using the SCANPST.EXE or Inbox Repair tool in Outlook. The steps are as follows:

    1. Close Outlook.
    2. On your PC, go to C:\Program Files\Microsoft Office/Officexx or C:\Program Files\Microsoft Office/root/Officexx folder. The SCANPST location may vary based on the Outlook or Windows version installed on your system.
    3. Find and launch the SCANPST.EXE program. 
    Find and launch the SCANPST.EXE program
    1. Click Browse and choose your PST file located at %localappdata%/Microsoft/Outlook or C:\Users\YourUserName\AppData\Local\Microsoft\Outlook.
    2. Once the PST file is selected, click the Start button.
    Once the PST file is selected click the Start button to initiate the analysis process.
    1. The tool will scan the PST file. If errors and inconsistencies are found, click the Repair button.
    2. The repair process may take a while – based on PST size and level of corruption. Wait for the repair process to complete.
    3. After the repair, restart the system and then launch Outlook.

    If the PST file you are trying to repair is larger than 2 GB, severely corrupt or damaged, or encrypted and password-protected, the SCANPST may fail. In case SCANPST crashes, stops responding, or fails to repair the PST file, you can use an advanced Outlook PST repair software, such as Stellar Repair for Outlook.

    Stellar Repair for Outlook is a professional PST repair software that can repair and fix severely corrupt or damaged PST files (as large as 50 GB or higher) and restore all mailbox components to their original form in a new healthy PST file. You can also directly export all the recovered mail items from the corrupt or inaccessible PST file to a live Exchange Server or a Microsoft 365 account in a few clicks. 


    The ERROR CODE 401 in the new Outlook for Windows can prevent users from accessing their emails or sending/receiving new emails. By following the troubleshooting steps and solutions mentioned above, you can resolve the Outlook not responding or crashing issue and the error code 401 without needing to seek further assistance. Make sure to follow and apply these solutions in the given order. If the problem is related to a corrupt PST file, you can use SCANPST or an advanced Outlook PST repair software, such as Stellar Repair for Outlook to repair the PST file.

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    About The Author

    Eric Simson linkdin

    Eric Simson is an Email Platform Consultant and is associated with Stellar Data Recovery from last 6 years. He writes about the latest technology tips and provides custom solutions related to MS Outlook, MS Exchange Server, Office 365, and many other Email Clients & Servers.

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