How to Fix Outlook Sync Issues

Start by checking whether your webmail or another device shows the same missing data, this tells you if the problem is server-side or limited to this Outlook installation. Then work through connection failures, folder-specific sync failures, profile or cache corruption, and Microsoft 365/Exchange account or service issues, in that order. Rebuilding or recovering the OST file is a fallback for stranded data, not a general sync repair method.

Outlook needs to stay connected to the mail server to keep your emails, calendar events, and contacts up to date. If this connection is interrupted, synchronization issues can occur, leading to delayed updates, missing messages, or folders that fail to update properly. In some cases, you may encounter send/receive emails, or Outlook may be unable to open the OST file linked to your account.

Syncing issues can arise from a disconnected client, service incident, damaged profile or cache, account configuration, or a folder-specific error. Diagnose the live mailbox and Outlook client first; recovering or converting an OST is not a method for repairing active synchronization.

In the sections that follow, we’ll walk you through a clear, step-by-step guide to identify the root cause of the sync error and apply practical solutions to get Outlook working normally again.

1. How to resolve the issue of Outlook not syncing in Windows?

   There are several methods to fix Outlook connection issues and Outlook not syncing emails with the server.

   • Method 1: Check the Work Offline status and connection indicators

     Before changing any settings, confirm that Outlook is actually trying to connect. Outlook shows its current connection state in the status bar at the bottom of the window, and this is the fastest way to rule out a simple offline toggle before you touch anything else.

     • Step 1: Check the status bar
       • Look at the bottom of the Outlook window for text such as ‘Connected,’ ‘Trying to connect,’ ‘Disconnected,’ or ‘Working Offline.’
     • Step 2: Turn off Work Offline mode if it's enabled
       • Go to the ‘Send/Receive’ tab in the ribbon.
       • If the ‘Work Offline’ button is highlighted, click it once to switch Outlook back online.
     • Step 3: Confirm the account has reconnected
       • Watch the status bar for ‘Connected’ or ‘All folders are up to date.’
       • If Outlook still shows ‘Disconnected’ or ‘Trying to connect,’ the issue is with the connection or the mail server rather than a setting inside Outlook, move on to the connection and service-health checks below.

     For Microsoft's full set of steps, see Work offline in Outlook for Windows.

   • Method 2: Check your internet connection

     If Outlook isn't syncing with your online account, there are a few steps you can take to find and fix the issue. Start by checking your internet connection, Outlook won’t be able to connect to the mail server if your connection is unstable or if your computer isn’t connected to a network at all. A weak or interrupted connection is often the reason Outlook fails to sync emails or update folders.

     • Step 1: Open Windows Settings in your computer
       • Click on the Windows Start button and select the ‘Settings’ icon.
     • Step 2: Go to the Network & Internet options
       • In the Settings window, click on ‘Network & Internet.’
       • On the Network & Internet page, click on ‘Status’ in the left-side menu.
     • Step 3: Check Internet Connection Status
       • On the Status page, look for the section labeled ‘Internet Connections.’
       • If your computer is connected to the internet, it should say ‘Connected.’
     • Step 4: Start the Network Troubleshooter
       • If not connected, click on the ‘Network troubleshooter’ to diagnose and fix internet connection issues.
       • If the troubleshooter can't resolve the issue, go to ‘Change adapter options’ in the left-side menu on the Status page.
     • Step 5: Diagnose and reset the Network Adapter
       • Right-click on the current network adapter and select ‘Diagnose’ to launch the adapter's built-in diagnostic tool.

         

       • If the diagnostic tool can't fix the issue, go to the adapter's Properties and click on ‘Configure.’
       • Go to the Advanced tab, find the ‘Reset’ option and click on it.
   • Method 3: Compare webmail with desktop Outlook and check Microsoft 365/Exchange service health

     Comparing what you see in webmail with what Outlook shows on your desktop tells you whether the problem sits with the mail server or with this particular Outlook installation.

     • Step 1: Check the same mailbox in a browser
       • Sign in to Outlook on the web (or your provider's webmail) using the same account.
       • Check whether the missing emails, folders, calendar events, or contacts are present there.
     • Step 2: Narrow down where the problem is
       • If webmail is current but the Outlook desktop app is stale, the issue is local to this Outlook installation, focus on the connection, profile, and cache checks in this guide.
       • If webmail is also missing the same data, the problem is on the Microsoft 365/Exchange or mailbox side, and no local Outlook fix will resolve it until the server-side issue clears.
     • Step 3: Check for a known Microsoft 365/Exchange service incident
       • If you're an administrator, check the Microsoft 365 Service Health dashboard in the admin center for open incidents affecting Exchange Online or Outlook.
       • Microsoft also publishes client- and service-specific sync incidents from time to time, for example this known mailbox folder sync issue. Check for a similar current advisory before making destructive local changes such as deleting the OST file or reinstalling Office.
   • Method 4: Close and restart Microsoft Outlook

     If the internet connection is fine, the next thing to do is restart both your computer and Outlook. Make sure Outlook and Windows are up to date by installing any pending updates. If syncing still doesn’t work, try resetting Outlook’s settings, this can resolve any configuration problems that might be interfering with the sync process.

     • Step 1: Close Outlook and restart your Computer
       • Click on the ‘File’ menu in Outlook and select ‘Exit’ or simply close the Outlook window.
       • Restart your computer to clear any temporary files or issues that may be causing the sync error.
     • Step 2: Open Outlook and check the sync status
       • After your computer has restarted, open Outlook and wait for it to load completely.
       • Go to your email folders and check if your emails are syncing properly.
     • Step 3: Check for Outlook Updates
       • If the sync issue still persists, go to the ‘File’ menu in Outlook and select ‘Office Account.’
       • Click ‘Update Options’ > ‘Update Now’ and check for any available updates to install them.

         

   • Method 5: Force Outlook to sync manually

     If you are getting the error message, Outlook folders not syncing, try syncing your emails and folders manually as described in the following steps. Note that 'Send/Receive All Folders' is a manual trigger, it does not replace or fully control how Exchange Cached Mode keeps your mailbox updated in the background, so use it to test whether a sync completes rather than as an ongoing fix.

     • Step 1: Open Outlook and go to Send/Receive
       • Open your Outlook application and wait for it to load completely.
       • In the Outlook main window, click on the ‘Send/Receive’ tab in the ribbon.
     • Step 2: Select Send/Receive All Folders
       • In the Send/Receive group, click on ‘Send/Receive All Folders.’
       • This forces Outlook to sync all of your email folders.

         

     • Step 3: Check the sync status and note any error
       • After a few moments, go to your email folders and check if your emails are syncing properly.
       • If the sync error still persists, open the Send/Receive Progress window, or check the Sync Issues folder covered later in this guide, and note the exact error message or status code. This tells you which of the causes further down this page you're actually dealing with.
   • Method 6: Change the Outlook send/receive sync frequency

     If you're experiencing Outlook sync issues, the Send/Receive schedule is worth checking. This setting controls how often classic Send/Receive groups run, it is not a universal 30-minute default for every account, and for Exchange or Microsoft 365 accounts running in Cached Exchange Mode, updates are largely driven by the server rather than this local timer. Adjusting it is most useful for POP and IMAP accounts, or as a general troubleshooting test.

     • Step 1: Open Outlook and go to File
       • Open your Outlook application and wait for it to load completely.
       • In the Outlook main window, click on the ‘File’ menu.
     • Step 2: Select Options > Advanced > Send and Receive
       • In the File menu, click on ‘Options’ and click on the ‘Advanced’ tab.
       • Scroll down to the ‘Send and Receive’ section.

         

     • Step 3: Change the Outlook Sync Frequency
       • In the Send and Receive section, click on ‘Send/Receive.’
       • In the Send/Receive Settings window, change the sync frequency to a lower value, such as 5 or 10 minutes.
       • Click ‘OK’ to apply the changes and close the Send/Receive Settings window.

         

     • Step 4: Check the email sync status
       • Go to your email folders and check if your emails are syncing properly.
       • If the sync error still persists, this setting is unlikely to be the cause, especially for Exchange or Microsoft 365 accounts. Move on to checking your profile and cache, or the server-side causes further down this page.
   • Method 7: Reconfigure the Outlook profile settings

     If you are having issues with Outlook not syncing across devices, one potential fix is to reconfigure your Outlook profile settings. This process varies depending on your specific Outlook version, but the general idea is to go into your Outlook settings and check/adjust your account settings, verify your user account credentials, and cache settings. By ensuring that these settings are all correct, you can often fix synchronization issues.

     • Step 1: Open Control Panel and go to Mail
       • Click on the Windows Start menu and type ‘Control Panel’ in the search bar.
       • In the Control Panel, click on ‘Mail (Microsoft Outlook 2016)’ under ‘Programs.’
     • Step 2: Open Mail Setup and select the profile
       • In the Mail Setup window, click on ‘Show Profiles.’
       • In the Mail dialog box, select the profile that you are using with Outlook.
       • Click on the ‘Properties’ > ‘Email Accounts’
       • Select the email account that you are using with Outlook and click on ‘Change.’

         

     • Step 4: Verify the Settings and apply the changes
       • In the Change Account window, verify that all of the account settings are correct.
       • Make sure that the incoming and outgoing server settings, email address, and password are all correct.
       • If any changes were made, click on ‘Next’ and then ‘Finish.’
       • Restart Outlook and check if the sync error has been resolved.
   • Method 8: Check your network and security settings

     When you are troubleshooting Outlook synchronization issues, one of the first things you should do is check your network, firewall and antivirus. One of the causes of this issue could be that your computer's security settings are blocking unwanted network requests from applications and email clients.

     • Step 1: Check your Network Connection
       • Make sure that your computer is connected to the internet and that you have a stable connection.
       • Try restarting your router or modem if needed.
     • Step 2: Disable Firewall and Antivirus temporarily
       • Disable the firewall and antivirus on your computer temporarily to see if it is causing the sync error.
       • To disable the firewall, go to the Windows Control Panel and click on ‘Windows Defender Firewall.’

         

       • In the Windows Defender Firewall window, click on ‘Turn Windows Defender Firewall on or off.’

         

       • Select ‘Turn off Windows Defender Firewall’ for both private and public networks and click ‘OK.’

         

       • The method to disable the antivirus may vary depending on the antivirus software that you are using.
       • Restart Outlook and check if the sync error has been resolved.
   • Method 9: Use SSL in Outlook to connect to your server

     Using SSL (Secure Socket Layer) in Outlook to connect to your email server can resolve sync errors. SSL encrypts the data being transmitted between Outlook and your email server, providing an extra layer of security. To use SSL in Outlook, modify your email account settings by enabling SSL, updating the port number for incoming and outgoing mail, and applying the changes.

     • Step 1: Open Outlook and navigate to Account Settings
       • Open the Microsoft Outlook application.
       • Click on the ‘File’ tab in the Outlook ribbon and then click on ‘Account Settings.’
       • In the Account Settings window, click on the ‘Email’ tab.
     • Step 2: Select the account and modify the Account Settings
       • Select the email account that you want to modify and click on the ‘Change’ button.
       • Check if you have configured your email account as POP3 or IMAP
       • In the Change Account window, click on ‘More Settings.’
       • In the Internet Email Settings window, click on the ‘Advanced’ tab.
     • Step 3: Enable SSL and update the Port Number
       • Select the option to ‘Use the following type of encrypted connection’
       • From the dropdown menu, choose ‘SSL (Secure Sockets Layer)’ as the type of encrypted connection.
       • Change the port number depending on the source server with which you want to synchronize your emails.
     • Step 4: Apply the Changes and test the connection
       • Click on ‘OK’ to apply the changes and close the windows.
       • Test the connection by sending an email to yourself or to someone else.
   • Method 10: Fix the root folder path (IMAP accounts only)

     The root folder path setting applies to IMAP accounts only, it has no equivalent for Exchange or Microsoft 365 accounts running in Cached Exchange Mode. If you're on an Exchange or Microsoft 365 account, skip this method and use the profile, cache, and service-health checks elsewhere in this guide instead. For IMAP accounts, this setting tells Outlook where to look for your mailbox folders on the server, and an incorrect or missing root folder path can cause sync problems. Updating it can prompt Outlook to reconnect properly and display all your folders as expected.

     • Step 1: Open Outlook and navigate to Account Settings
       • Open the Microsoft Outlook application.
       • Click on the ‘File’ tab in the Outlook ribbon and then click on ‘Account Settings.’
       • In the Account Settings window, click on the ‘Email’ tab.
     • Step 2: Select the email account and modify Account Settings
       • Select the email account that you want to modify and click ‘Change’
       • In the Change Account window, click on ‘More Settings.’
       • In the Internet Email Settings window, click on the ‘Advanced’ tab.
     • Step 3: Change the Root Folder Path and apply the changes
       • In the Advanced tab, under ‘Root folder path,’ type in the correct location of the root folder of your mailbox.
       • The default path is usually ‘Inbox.’
       • Click on ‘OK’ to apply the changes and close the windows.
   • Method 11: Repair the email account in MS Outlook

     Repairing your email account in Outlook can fix incorrect settings that might be causing sync problems. It can also help clear out any damaged or corrupt files that could be affecting performance. This process often restores proper communication between Outlook and the mail server. Below are the steps to repair your account and get syncing back on track.

     • Step 1: Open Outlook and navigate to Account Settings
     • • Open the Microsoft Outlook application.
       • Click on the ‘File’ tab in the Outlook ribbon and then click on ‘Account Settings.’
       • In the Account Settings window, click on the ‘Email’ tab.
     • Step 2: Repair the Email Account and test the connection
       • Select the email account and click ‘Repair’
       • Follow the on-screen instructions to complete the repair process.

         

   • Method 12: Check the Sync Issues folder for diagnostic evidence

     When Outlook synchronizes with the mail server, it creates a Sync Issues folder and logs information about failed sync attempts there. Review the Conflicts, Local Failures, and Server Failures subfolders as diagnostic evidence, the specific errors logged there point to which cause on this page you're dealing with. Deleting these items clears the log, it does not fix the underlying synchronization problem, so treat this as a way to gather information rather than a repair step.

     • Step 1: Open Outlook and click the menu icon
       • Open the Microsoft Outlook application.
       • Click on the menu button and click ‘Folders’

         

     • Step 2: Review the logged errors
       • Expand the Sync Issues folder and open the Conflicts, Local Failures, and Server Failures subfolders.
       • Open a few recent items and note the error description or code shown for each, this indicates whether the failure is connection-related, account-related, or server-side.
       • Once you've noted the relevant errors, you can clear the folder's contents to keep it tidy. Doing so is optional housekeeping and does not itself resolve the sync issue.
       • Close and restart the Microsoft Outlook application.

         

   • Method 13: Rebuild the OST file after confirming server data is healthy

     When an Outlook profile is created, a corresponding Offline Storage Table (OST) file is also created. This OST file is a replica of the user's Exchange mailbox and enables offline access to the mailbox data. If the OST file becomes corrupted, it can prevent Outlook from opening or syncing the mailbox, whether this actually results in data loss depends on whether the server still holds a current copy and what unsynced changes, if any, exist only in the local file. Before deleting the OST file, use the service-health and webmail comparison above to confirm the server-side mailbox is complete and up to date. Deleting the OST file and rebuilding the Outlook profile creates a fresh OST file synced from the server, and can resolve synchronization issues once server data is confirmed healthy.

     • Step 1: Close Outlook and locate the OST file
       • Close the Microsoft Outlook application.
       • Open File Explorer, navigate to the location where your email account data files are stored, and locate the OST file associated with the email account that is experiencing the sync error.

         The OST file is typically located in the following location in Outlook 2019, 2016 and 2013.

         C:Users<username>AppDataLocalMicrosoftOutlook

         The OST file is typically located in the following location in Outlook 2010

         C:Users<username>AppDataLocalMicrosoftOutlook

         The OST file is typically located in the following location in Outlook 2007

         C:Documents and Settings<username>Local SettingsApplication DataMicrosoftOutlook

     • Step 2: Back up, then delete the OST file
       • If any offline or local-only changes might matter, copy the existing OST file to a separate backup location before deleting it, once deleted, only a surviving copy can supply data Outlook doesn't redownload from the server.
       • Right-click on the OST file and select ‘Delete.’
       • Confirm the deletion by clicking ‘Yes’ in the confirmation prompt.
     • Step 3: Open Control Panel and add a new profile
       • Open the Control Panel on your computer.
       • Open Mail (32-bit): In the Control Panel, click on the ‘Mail (32-bit)’ option.
       • In the Mail Setup window, click on the ‘Show Profiles’ button, then click on the ‘Add’ button.
     • Step 4: Name the profile and add an email account
       • In the ‘New Profile’ window, provide a name for the new profile and click ‘OK.’
       • In the new profile, follow the prompts to add the email account that was previously deleted.
       • Close the Mail Setup window and restart the Microsoft Outlook application.
       • Check if Outlook is able to connect to the server and the sync issue is resolved.

         

       Note: When you use this method to rebuild or configure a new email profile, Outlook creates a new OST file and syncs it with the mailbox server. As a result, any changes that existed only in the previous OST file and were never synced to the server are lost. For instance, if the server goes down and you have important emails only in your local OST file, you won't be able to restore them through this method. To recover the readable data from that local snapshot before it's replaced, use a third-party converter tool such as EdbMails, as described in the following step.

   • Method 14: Repair and reinstall Microsoft Office (last resort)

     Treat repairing or reinstalling Office as a late-stage step, exhaust the connection, profile, service-health, and OST rebuild checks earlier in this guide first, since they resolve most sync issues without a full uninstall. That said, an outdated version of Outlook or Microsoft Office can contribute to sync failures, and in many cases updating Office to the latest version or running a quick repair is enough to restore normal syncing.

     • Step 1: Open Control Panel and select Microsoft Office
       • Click on the Windows Start menu and open the Control Panel.
       • In the Control Panel, click on ‘Programs and Features.’
       • Find Microsoft Office in the list of installed programs and click on it.
     • Step 2: Repair Office and relaunch Outlook
       • Click on ‘Change’ and then select ‘Repair’.
       • Follow the on-screen instructions to complete the repair process.

         

     • Step 3: Uninstall Microsoft Office if the repair is unsuccessful
       • Find Microsoft Office in the list of installed programs and click on it.
       • Click on ‘Uninstall’ and follow the on-screen instructions to uninstall Microsoft Office.

         

     • Step 4: Download and install the latest version of Office
       • Download the latest version of Microsoft Office from the official Microsoft website.
       • Run the installer and follow the on-screen instructions to install Microsoft Office.
     • Step 5: Open Outlook and set up your Email Account
       • Open the Microsoft Outlook application.
       • If prompted, set up your email account by entering your email address and password.
       • Test the connection by sending an email to yourself and verify if the Outlook sync issue is resolved.
   • Method 15: Recover OST Data with EdbMails OST to PST Converter

     EdbMails does not repair live Outlook synchronization. Use OST recovery only after the connection, service, account, profile and cache checks above, and only when the live mailbox cannot supply required data or the preserved OST contains unique local content.

     If the mailbox/profile cannot be restored and required data exists only in the old OST, use the EdbMails OST to PST Converter to scan the preserved file, preview readable mailbox data, and export the required content to PST.

     For the complete recovery and export procedure, see the OST to PST conversion guide.

     Scanning and preview can be performed independently of the original Outlook profile. Use the appropriate supported workflow for PST export or direct migration to Microsoft 365 or Exchange.

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Additional Resources:

• EdbMails OST to PST Converter
• Fix Outlook not Connecting to Server Error
• Fix Outlook the set of folders cannot be opened
• Outlook Cached Exchange mode
• Fix Outlook not syncing error
• Fix Outlook data file cannot be accessed
• Fix the error Outlook inbox not updating