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The set of folders cannot be opened in Outlook [Solution]

The “The set of folders cannot be opened” error in Outlook often occurs due to issues with your Outlook data files, such as a corrupted PST or OST. When this occurs, you may be unable to access your emails, calendar, contacts, and other essential mailbox items, bringing your workflow to a halt.

A reliable way to resolve this problem is by using EdbMails PST Repair Tool. This tool allows you to recover data from damaged or orphaned OST files by converting them to PST format, making it easy to restore your mailbox and access your Outlook data even when Outlook itself won’t open.

In this step-by-step guide, we’ll explore the common causes behind the error, how to identify its symptoms, and the most effective methods to fix it and get Outlook running smoothly again.

EdbMails OST to PST Converter

There are several factors that can contribute to the ‘Cannot start Microsoft Outlook set of folders’ error, including:

PST file corruption: The PST file, which stores all of a user's data in Microsoft Outlook, can become corrupted due to various reasons such as hardware failures, software bugs, power outages, improper shutdowns, outdated Outlook versions, or interference from antivirus programs.
Improper shutdown: If you shut down your computer improperly, such as by using the power button, it can cause the PST file to become corrupt and trigger the error message.
Outdated software: If you are using an outdated version of Microsoft Outlook, it can cause compatibility issues that result in the ‘The set of folders cannot be opened in Outlook’ error.
Antivirus software: Antivirus software can sometimes interfere with the operation of Microsoft Outlook, causing the error ‘Cannot start Outlook the set of folders cannot be opened’ to appear.

What are the symptoms of the error ‘The set of folders cannot be opened in Outlook’?

The following are some of the symptoms of the Outlook error:

Error message: When you try to open Outlook, you receive the error message ‘Cannot start Microsoft Outlook the set of folders cannot be opened’.
Inability to access email: If the error message appears, you will be unable to access your email, calendar, contacts or other important data stored in your Outlook account.
Slow performance: If the error message appears, you may notice that Microsoft Outlook is running slow or has become unresponsive.

How to resolve the issue ‘Outlook this set of folders cannot be opened’?
The most likely cause of the error is a corrupted PST file associated with your account. If Outlook cannot connect to the server or if you are unable to access your email data as a result of the error, try the following solutions for Microsoft 2016, 2019, and 2013. The following methods are also applicable to Windows 10, 11, 8, and 7 systems.
- Method 1: Close and relaunch Outlook
  This method offers a simple and effective first step to resolve the error ‘Cannot start Microsoft Outlook the set of folders’. When Outlook launches, it connects to the mail server, loads essential files and settings, and initializes the program. However, temporary network issues, corrupted data files, or outdated settings can interrupt this process and trigger the error. Restarting Outlook helps re-establish a clean connection to the server, which may resolve the issue.
  If the problem continues, proceed with more advanced solutions like running the Inbox Repair Tool or creating a new PST file.
  - Step 1: Close Microsoft Outlook and restart your computer
    To close Microsoft Outlook, click on the ‘File’ menu in the top-left corner of the screen
    Click ‘Exit’.
    Restart your computer, which can help to clear any temporary data that may be causing the error.
  - Step 2: Reopen Microsoft Outlook and check for the error
    After restarting your computer, open Microsoft Outlook.
    Check to see if the ‘The set of folders cannot be opened in Outlook’ error has been resolved.
    You should now be able to access your email, calendar, and other important data.
- Method 2: Start Outlook in Safe mode
  Starting Outlook in Safe Mode can help fix the error “The set of folders cannot be opened” by launching the application with only its essential components. In this mode, Outlook disables third-party add-ins, custom settings, and customizations—helping you determine whether one of these is causing the issue. If Outlook works correctly in Safe Mode, it’s likely that a faulty add-in or configuration is to blame. This method is also useful if your system is affected by viruses or malware, as it limits the influence of potentially harmful components.
  - Step 1: Open Microsoft Outlook
    To close Microsoft Outlook, click on the ‘File’ menu in the top-left corner of the screen
    Click ‘Exit’ to close Microsoft Outlook and all of its associated processes.
  - Step 2: Start Microsoft Outlook in Safe Mode
    While holding down the Ctrl key, double-click on the Microsoft Outlook icon to open it.
    This launches a dialog box asking if you want to start Outlook in safe mode.
    Click ‘OK’ to proceed and choose the Outlook profile name.
  - Step 3: Verify if the error is resolved
    After you open Microsoft Outlook in Safe mode, check to see if the error has been resolved.
    You should now be able to access your email, calendar, and other important data.
  - Step 4: Exit Safe mode and restart Outlook
    After you have verified that the error has been resolved, exit Safe mode by closing Microsoft Outlook.
    Restart the application normally, without holding down the Ctrl key.
- Method 3: Disable conflicting Outlook Add-ins
  The error message ‘Cannot open Outlook set of folders’ can also be caused by various factors including conflicting add-ins. Add-ins are third-party tools or components that extend the functionality of Outlook. However, some add-ins may cause compatibility issues or slow down the performance of the application. If an add-in is causing the error, disabling it can help resolve the issue. If the error is resolved, you can re-enable the add-ins one by one to determine which add-in is causing the problem.
  Note: It's recommended to keep only essential add-ins enabled and disable all others, to maintain optimal performance and stability of Outlook.
  - Step 1: Open Microsoft Outlook
    Open Microsoft Outlook by double-clicking the desktop icon or finding it in the list of installed programs.
  - Step 2: Access Outlook Options and go to the Add-ins page
    To access the Outlook Options, click on the ‘File’ menu in the top-left corner of the screen
    Click ‘Options.’
    In the Outlook Options window, click on ‘Add-ins’
  - Step 3: Disable the conflicting Add-ins
    To disable an add-in, click on the ‘COM Add-ins’ option
    Uncheck the box next to the Add-in and click ‘OK’
    Repeat this step for each conflicting Add-in
  - Step 4: Restart Microsoft Outlook
    After disabling the conflicting add-ins, close Microsoft Outlook
    Reopen it to see if the ‘The set of folders cannot be opened in Outlook’ error has been resolved.
- Method 4: Disable and enable the Antivirus software
  Temporarily disabling and re-enabling your antivirus software can sometimes resolve the ‘The set of folders cannot be opened in Outlook’ error. Antivirus programs may interfere with Outlook’s processes by blocking certain actions or files. Restarting the antivirus can help clear these conflicts and restore normal operation. To prevent similar issues in the future, it's recommended to add Outlook to the antivirus whitelist or exclusion list.
  - Step 1: Locate the antivirus software in your computer
    Look for the antivirus software in the system tray or in the list of installed programs from the ‘Start Menu’
  - Step 2: Disable the antivirus software
    Right-click on the antivirus software icon and select the option to disable or turn off the antivirus software.
    Some antivirus software may require you to enter a password or confirm that you want to disable it.
    If you are using Windows Security, go to ‘Virus and threat protection’ > ’Manage Settings’ and turn off the monitoring temporarily.
  - Step 3: Restart Microsoft Outlook
    After disabling the antivirus software, close Microsoft Outlook.
    Reopen it to see if the "The set of folders cannot be opened in Outlook" error has been resolved.
    If the error has been fixed, you can re-enable the antivirus software again.
- Method 5: Delete the XML files from Outlook directory
  The XML file in the Outlook directory is responsible for storing the user's profile and customization settings. If this file is corrupt or contains incorrect information, it can prevent Outlook from opening correctly, resulting in the ‘The set of folders cannot be opened’ error. Deleting the XML file from the Outlook directory can help solve the error by removing any corrupt or incorrect entries from the file
  - Step 1: Locate the Outlook data files folder
    Open the Windows File Explorer
    Navigate to the following location:
    C:\Users\AppData\Local\Microsoft\Outlook
    by replacing the Username with your computer name.
  - Step 2: Delete the XML files from the folder
    In the Outlook folder, find and delete all the XML files.
    Do not delete any other files besides the XML files.
  - Step 3: Restart Microsoft Outlook
    After deleting the XML files, close Microsoft Outlook and then reopen it to see if the error has been resolved.
- Method 6: Delete your account from the Windows Mail App
  The error ‘Outlook set of folders cannot be opened’ can be caused by multiple factors, one of which is the presence of multiple email accounts in the Windows Mail App. The Windows Mail App is an email client integrated into Windows 10, and it can be the source of the conflict with Outlook, leading to the error message. When you remove an email account from the Windows Mail App, you reduce the number of email accounts, resolving the conflict between the two email clients and allowing Outlook to open the set of folders without any problems.
  It is important to note that deleting the account from the Windows Mail App does not delete the email account or the data associated with it. The data will still be available on the email server and can be accessed through other email clients or webmail services.
  - Step 1: Open the Windows Mail App
    Click on the ‘Windows Mail App’ icon on your taskbar or in the list of installed programs to open the app.
    Once the Windows Mail App is open, click on the gear icon in the bottom left corner to access the Settings section.
  - Step 2: Delete the account from Account settings
    In the Settings section, click on the option to manage accounts.
    Then, select the account that you want to delete and click on the option to remove or delete the account.
    You will be prompted to confirm the deletion of the account.
    Click ‘Delete’ to confirm the deletion.
- Method 7: Reconfigure the Outlook user profile
  Reconfiguring the Outlook user profile can help solve the error ‘Outlook folders cannot be opened’. When you create a new Outlook profile, it creates a new set of data files that stores information such as your email messages, calendar, contacts, and other items, which helps to resolve any corruption or failure to update inbox and folders that may be causing the error message to appear.
  For instance, if your original Outlook profile is experiencing issues with the data files, reconfiguring the profile creates a new data file set, which eliminates any corruption or misconfiguration in the original data files. This can also help to resolve compatibility issues that may be affecting the performance of Outlook. Additionally, reconfiguring the Outlook profile resynchronizes the data files from the server.
  - Step 1: Close Outlook and open Control Panel
    Close Microsoft Outlook completely before you start reconfiguring your user profile.
    Open the Control Panel on your computer by clicking on the Start menu and typing ‘Control Panel’ in the search bar.
    You will be prompted to confirm the deletion of the account.
    Click on the Control Panel option to open it.
  - Step 2: Choose Mail (Microsoft Outlook 2016)
    In the Control Panel, click on the option for ‘Mail (Microsoft Outlook 2016)’ to open the Mail Setup dialog box.
    In the Mail Setup dialog box, click ‘Show Profiles’.
  - Step 3: Delete the old email profile from Outlook
    In the Mail dialog box, select the profile that you want to delete.
    Click ‘Remove’
  - Step 4: Create a new profile and set it as default
    After removing the old profile, click ‘Add’ to create a new profile.
    Follow the prompts to set up the new profile by entering your email account information and password.
    In the Mail dialog box, select the new profile that you created and then click ‘Set as Default’ to set it as the default profile.
- Method 8: Reset the Outlook navigation pane
  The navigation pane in Outlook displays the folders and items in the mailbox and any corruption or customization made to it can lead to issues when trying to open the mailbox. Resetting the Outlook navigation pane can help solve the error ‘Microsoft Outlook cannot open the set of folders’ by removing any customizations made to the navigation pane and restoring it to its default settings.
  - Step 1: Close Outlook on your computer
    Close Microsoft Outlook completely before you start resetting the navigation pane.
  - Step 2: Hold down the Ctrl key and launch Outlook
    Start by holding down the ‘Ctrl’ key on your keyboard.
    While holding down the Ctrl key, double-click on the Microsoft Outlook icon on your desktop or in your list of programs to launch the application.
    This opens Outlook in the Safe mode
  - Step 3: Restore the Navigation Pane:
    In Outlook, go to the View tab, then select ‘Reset View’ to reset the navigation pane.
- Method 9: Configure App password for Outlook
  Performing a Mailbox Cleanup in Outlook can help to resolve the ‘The set of folders cannot be opened’ error in Outlook 2016 and 2019 by removing any unwanted items or corrupt data from your mailbox. Compacting the data file and repairing the data file if needed, can also help to resolve any performance issues and improve the overall stability of your Outlook experience.
  - Step 1: Enable Two-Step Verification
    To use an App Password for Outlook, you must first enable two-step verification for your Microsoft account. If your account is already enabled with the two-step verification, proceed with the following step.
    Open your Microsoft account security settings by visiting the Microsoft website.
    Look for the two-step verification option and turn it on if it is not already enabled.
    Follow the on-screen instructions to set up two-step verification.
  - Step 2: Generate an App Password
    Next, you'll need to generate an App Password for Outlook.
    In the Microsoft account security settings, find the section for app passwords.
    Select ‘Create a new app password’ and make sure to save it somewhere secure
  - Step 3: Enter the App Password in Outlook
    Finally, you'll need to enter the App Password you just generated into Outlook.
    Open Microsoft Outlook on your computer.
    Go ’File’> ‘Account Settings’ section in Outlook.
    Reconfigure your account by entering the App Password you generated earlier.
    Save the changes and restart Outlook.
- Method 10: Perform a Outlook Mailbox Cleanup
  Performing a Mailbox Cleanup in Outlook can help to resolve the ‘The set of folders cannot be opened’ error in Outlook 2016 and 2019 by removing any unwanted items or corrupt data from your mailbox. Compacting the data file and repairing the data file if needed, can also help to resolve any performance issues and improve the overall stability of your Outlook experience.
  - Step 1: Run the Mailbox Cleanup Tool
    Open Microsoft Outlook and go to the ‘File’ menu.
    Select ‘Tools’ and then ‘Mailbox Cleanup’.
    Use the Cleanup tool to remove any unwanted items from your mailbox, such as deleted items, large attachments, and more.
    Choose the cleanup options you want to perform and select the ‘Clean Up’ button to start the cleanup process.
  - Step 2: Compact the Outlook Data File
    After running the Mailbox Cleanup tool, you may also want to compact your Outlook data file to help improve performance.
    In Outlook, go to the ‘File’ menu > ‘Info’ and ‘Account Settings’
    Click the ‘Data Files’ tab and choose the data file you want to compact from the list of data files.
    Click ‘Settings’ and then choose ‘Compact Now’.
    Microsoft Outlook starts compacting the file, which may take some time depending on the size.
  - Step 3: Repair the Outlook Data File
    If compacting the data file does not resolve the issue, you may need to repair the data file.
    Open the Inbox Repair Tool (also known as Scanpst.exe) on your computer. To locate the scanpst tool, navigate to the following locations:
    Microsoft Outlook 2019:
    C:\Program Files (x86)\Microsoft Office\root\Office16
    Microsoft Outlook 2016:
    C:\Program Files (x86)\Microsoft Office\root\Office16
    Microsoft Outlook 2013:
    C:\Program Files (x86)\Microsoft Office\Office15
    Microsoft Outlook 2010:
    C:\Program Files (x86)\Microsoft Office\Office14
    Choose the data file you want to repair and click ‘Start’
    After the scanning is complete, click ‘Repair’ to start repairing the Outlook data file.
- Method 11: Disable Outlook compatibility mode
  Enabling Compatibility Mode for an earlier version of Windows can interfere with Outlook’s normal operation and lead to errors. Disabling this mode allows Outlook to run using the current Windows version, which can help resolve compatibility issues and restore access to your emails and folders.
  - Step 1: Open Outlook in Windows
    Go to the Start menu and search for ‘Microsoft Outlook’
    Right-click on the Microsoft Outlook icon and select ‘Run as administrator’
    If prompted, enter your Windows login credentials to continue.
  - Step 2: Disable Compatibility Mode in Outlook
    Click on ‘File’ in the Outlook main menu
    Click on ‘Office Account’ and Select ‘About Outlook’
    Look for ‘Outlook is in compatibility mode’ at the bottom of the window
    If compatibility mode is enabled, click on the ‘Change Settings’ button
    In the ‘Compatibility Mode Settings’ window, uncheck the option ‘Run this program in compatibility mode for’
    Click ‘OK’ to save the changes.
  - Step 3: Restart Outlook and verify the change
    Close the Outlook application.
    Open Outlook again by following the same steps in Step 1.
    Go to ‘File’ in the Outlook main menu
    Go to ‘Office Account’ and Select ‘About Outlook’
    Check if ‘Outlook is in compatibility mode’ is still present at the bottom of the window. If it is not present, then the compatibility mode has been successfully disabled.
- Method 12: Export the OST file to PST from Outlook
  The OST file is a locally cached copy of your mailbox data, created when Cached Exchange Mode is enabled in Outlook. If you're facing issues with a corrupted PST file, exporting the OST to a new PST can help bypass the error and restore access to your data. This method works only if the original mailbox server is still accessible and the OST file is connected to your account. However, if the OST file becomes orphaned you’ll need a dedicated recovery tool like EdbMails OST to PST Converter. It allows you to recover data from orphaned OST files and export them safely to PST format, even if Outlook can’t connect to the server.
  - Step 1: Launch Import and Export Wizard in Outlook
    Launch Outlook and click on the ‘File’ menu.
    Select ‘Open & Export’ and then click on ‘Import/Export’
  - Step 2: Export the OST file to PST file format
    From the Import and Export wizard, select ‘Export to a file’ and click on ‘Next’
    Select ‘Microsoft Outlook Data File (.pst)’ as the file type and click on ‘Next’
    Choose the mailbox or folder that you want to export, and click on ‘Next’
    You will be prompted to set a password for the exported PST file (optional).
    Click ‘OK’ to start the export process.
  - Step 3: Import the PST into Microsoft Outlook
    Wait until the export process is completed.
    You can view the exported PST file in the location specified.
    To retrieve all your emails, folders and mail items, open Outlook and import the PST file by following the preceding steps and selecting ‘Import from another program or file’>
- Method 13: Repair Outlook and Microsoft Office
  To repair your Microsoft Outlook profile follow these steps:
  - Step 1: Open Outlook and go to File
    Open Microsoft Outlook on your computer.
    Click on the ‘File’ tab in the upper-left corner of the screen.
  - Step 2: Go to Account Settings and repair the email account
    Click on the ‘Account Settings’ option, and then click on ‘Account Settings’ again in the drop-down menu.
    Select the email account that you want to repair, and click ‘Repair’.
  - Step 3: Reconfigure the profile and restart Outlook
    Follow the on-screen instructions to repair your email account.
    Enter your email account credentials and configure various settings when prompted.
    Once the repair process is complete, restart Microsoft Outlook and check if the issue has been resolved.
  To repair Microsoft Office follow these steps:
  - Step 1: Launch Control Panel in your computer
    Click on the Windows Start button in the lower-left corner of your screen.
    In the search bar, type ‘Control Panel’ and click on the result.
    In the Control Panel window, look for ‘Programs and Features’.
  - Step 2: Locate Microsoft Office in the list of installed programs
    Scroll through the list of installed programs to find Microsoft Office.
  - Step 3: Start the Repair wizard to repair Microsoft Office
    Right-click on the Microsoft Office program and select ‘Change’
    Click ‘Quick Repair’ to start the repair process.
    The repair process may take a few minutes to complete, depending on your system and the size of the installation.
  - Step 4: Restart your computer and relaunch MS Office
    After the repair process has completed, restart your computer to ensure the changes take effect.
    Launch Microsoft Office again to verify that the repair was successful and use the application normally without the error.
- Method 14: Install a different version of MS Office
  The set of folders cannot be opened in Outlook error often occurs due to a corrupted Outlook profile or data file. If you're currently using the 32-bit version of Microsoft Office, upgrading to the 64-bit version is recommended for enhanced stability and performance.
  A 64-bit version of Office provides a more robust environment for Outlook, especially when handling large mailboxes or complex profiles. This can help prevent errors caused by Outlook attempting to access unavailable or damaged folders, offering a more reliable experience overall.
- Method 15: Use EdbMails to fix Outlook set of folders cannot be opened
  EdbMails is a helpful tool to fix the ‘The set of folders cannot be opened’ error in Outlook 2016 and 2019, especially if the original PST file is damaged and can’t be fixed using tools like ScanPST or by repairing the Outlook profile.
  It works with both OST and PST files, making it a flexible option for repairing different types of Outlook data. EdbMails uses advanced scanning to detect and fix problems, even in severely corrupted files. The tool works with all versions of Windows and Outlook, and lets you recover emails, contacts, calendars, and other important data without any loss.
  Here’s how you can use EdbMails to resolve the error ‘Outlook set of folders cannot be opened’:
  - Step 1: Download and install EdbMails repair tool for OST to PST
    Download and install the EdbMails application on any Windows-based computer.
    Enter your email address and password to log in, or click ‘Start Your Free Trial’ to explore the features without setting up an account.
    Select ‘Outlook PST Recovery and Migration’.
    Select ‘OST to PST’.
    You can use the default job name or click ‘New Job’ to change it.
  - Step 2: Select the offline OST file
    Click ‘Browse for OST file'.
    Choose the offline OST file from your computer and click ‘Next’ to continue. If the OST file is stored on a network, make sure it’s shared with both read and write permissions enabled.
    Click ‘Browse’.
    Select the location to save the exported PST files. Ensure you have enough free disk space for storage.
  - Step 3: Preview and select the mailbox
    EdbMails starts scanning the OST file and may take a few minutes to complete depending on the size of the OST file.
    After the repair is finished, you’ll see the full folder structure on the left side. Simply expand the mailbox and its folders to preview the contents. The preview pane lets you view emails, contacts, notes, tasks, calendars, and more—right within the application.
    Select the required mailboxes/folders and click the ‘Next’ button.
  - Step 4: Export Outlook PST files
    Verify the mailboxes and folders selected for export operation.
    EdbMails lets you customize your export using filters. For example, you can set a date range to export only specific items. To apply filters, just click the ‘Settings’ button.
    Date filter settings for PST to PST conversion .
    Make sure the ‘Action’ is set to 'Export', then click the 'Start Export' button.
    The export operation is now initiated, and you can monitor it in the progress bar. Once the process is complete, EdbMails will display the export operation completion message.
    Import the healthy PST file into Outlook to recover all your mail items and folders.