Proven Solutions To Fix Outlook Sync Issues

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Outlook is one of the most popular email clients, used by millions of people around the world. However, despite its widespread use, it’s common for users to experience Outlook sync issues that can disrupt their productivity and cause frustration. 

Slow internet connection, outdated or corrupt Outlook installation, incorrect or outdated login credentials, incompatible add-ins or plugins, Anti-virus software or security system settings blocking Outlook, and outdated operating system or device drivers are some of the reasons that trigger synchronization issues in Outlook.

Fortunately, there are several solutions to these problems, and in this article, we’ll explore some effective ways to fix Outlook sync issues quickly and easily. Whether you’re a seasoned Outlook user or new to the platform, our tips will help you get your email back on track and avoid future issues.

How To Fix the Synchronization Issue in Outlook?

Solutions like checking the internet connection, restarting Outlook, verifying and correcting the Outlook settings, checking the storage space of your Outlook Mailbox, checking pending Outlook updates, disabling Anti-virus software, removing Outlook cache, repairing Outlook data files, and recreating Outlook profile are some of the solutions that can help any Outlook user who has faced Outlook sync errors.  

Table of Contents:

Identifying the cause of sync issues is important to fix the problem in Outlook effectively. 

Solution 1: Restart The Outlook Application To Fix Outlook not syncing Problem

Restarting the Outlook application results in re-establishing the connections to the mail server and restarting any pending tasks or stalled processes essential for synchronization.

A simple reboot or restart can help you fix various issues, including the Sync issues.

Solution 2: Check Internet Connectivity To Fix Outlook Folder Not Syncing Issue

A poor or unstable internet connection can cause sync issues, so ensure you have a stable and reliable connection. One of the first steps in fixing Outlook email sync issues is to check your internet connection. If you’re using a Wi-Fi connection, try moving closer to your router or restarting it. You can also try using a wired Ethernet connection for a more stable connection.

If your internet connection is working fine, but you’re still experiencing sync issues in Outlook, try the other troubleshooting steps outlined in this article.

Solution 3: Verify Outlook Settings To Resolve Sync Issues on Outlook

Outlook relies heavily on correct credentials such as email address and login password to communicate with the mail server. So, adding incorrect email addresses or passwords prevents authentication, which also halts the syncing process. At times, you might also have also changed or modified other settings like user name, mailbox location, or added a different mail server. 

Therefore, verifying Outlook settings and credentials might help you connect to your Outlook server, potentially fixing the Outlook syncing issue. 

Solution 4: Check for any Pending Outlook Updates

Checking for any pending Outlook Updates and upgrading to the latest version is one of the best solutions to not only Microsoft Outlook not syncing issues but various other minor and severe issues and problems in Outlook.

By updating your Outlook application to the latest version, you can ensure that any bugs or glitches are fixed and that the application runs smoothly. This can help to fix Outlook sync issues and prevent future problems. 

Steps to update the Outlook application to fix sync issues:

  • Open Outlook and click on the File tab in the top left corner of the screen.
  • Click on Office Account or Account, depending on your version of Outlook.
  • Click on Update Options and then select Update Now. Wait for Outlook to check for available updates.

check for any pending Outlook Update to fix the Outlook sync issues

  • If an update is available, click on Update to start the installation process.
  • Follow the prompts to complete the installation.
  • Once the update is installed, restart Outlook and check if the issue is resolved.

Solution 5: Verify if Your Mailbox is full

Outlook mailbox might reach or cross its storage limits. So new emails might not appear in your inbox, you may be unable to download new attachments, changes made might get reflected, and sent emails might not get displayed in the sent folder are some of the most common indicators of this cause. You might also encounter error messages warning you about insufficient space; one might also feel performing certain tasks takes longer time, etc. 

In that case, the best solution is to delete older emails or move important files and documents to external storage devices.  

Solution 6: Check and Disable Firewall and Anti-virus Software To Fix Sync Issues in Outlook

Tools and programs like the Firewalls and other Antivirus programs are built to protect your computer from viruses, malware, and other unauthorized access. However, these utilities might sometimes interfere with legitimate software like Microsoft Outlook. 

Firewalls and antivirus tools might block particular ports and protocols for mail syncing. At times, they might also prevent Outlook from connecting to the servers. 

In such cases, the best solution is to disable Firewall and other installed Anti-Virus software and see if these utilities were at fault. 

Solution 7: Try Disabling Third-party Outlook add-ins That Might Trigger sync errors in outlook

Installing or using any third-party add-ins might sometimes interfere with Outlook’s core operations and functionality, triggering the syncing issue. Also, using any outdated or incompatible add-ins might not work in accordance with the newer versions of Outlook, which might also be the reason that has caused the sync error.

Disabling the add-ins can help users prevent conflicts and resolve problems, ensuring Outlook runs smoothly.

Steps to remove a faulty add-in to fix synchronization errors in Outlook:

  • Open Outlook and click on the File tab in the top left corner of the screen.
  • Click on Options and then select Add-ins from the left-hand menu.
  • In the Manage dropdown menu at the bottom of the screen, select COM Add-ins and click on Go.

Disable Outlook Add-ins to resolve Outlook not syncing

  • Uncheck the box next to any add-ins that you suspect may be causing the sync issue.

Disable Third-party Outlook add-ins to resolve sync errors in outlook

  • Click OK to save your changes.
  • Restart Outlook and check if the issue has been resolved.

Solution 8: Remove Outlook Cache and Temp Files

Microsoft Outlook stores temporary files, including emails, calendar data, passwords, and settings, to speed up the application’s performance and allow offline access. Over time, these cache and temp files will become oversized, cluttered, or, in rare cases, corrupted, which might lead to Outlook syncing issues. It can also be due to the presence or availability of outdated or incorrect cached data.

Therefore, clearing up the cache or Temp files can help resolve performance issues and temporary glitches and, in most cases, get rid of the sync issues.

Steps to remove Outlook cache and Temp files:

  • Close the Outlook application.
  • Hit the Win + R keys to open the Run command, type in “%localappdata%\Microsoft\Outlook\Roamcache” and click on the OK button.
  • Find and delete the .ost file (if you use Exchange accounts) or .pst file (if you use IMAP or POP accounts).
  • Once you have deleted Outlook the Temp or the Outlook cache files, you can restart the Outlook application. 

Solution 9: Repair Outlook PST Files To Fix Outlook Syncing Issues

Outlook PST files (Personal Storage Table files) save user Outlook data, including emails, contacts, calendars, attributes, settings, tasks, notes, etc. These files work as local archives for smooth synchronization and uninterrupted offline access.

However, these PST files might become oversized or corrupt, preventing the Outlook application from syncing properly. 

So, if you think your PST file is the reason behind the Outlook not syncing issue. Then, you can try repairing the PST files using SCANPST.EXE or a reliable PST Repair tool. 


The ScanPST.exe tool is a useful built-in tool in Outlook that can help to repair corrupt PST files and fix sync issues. Here are the steps to repair a corrupt PST file using the ScanPST.exe tool:

  • Close Outlook and navigate to the location of the exe tool on your computer.

Note: The location of the ScanPST.exe tool may vary depending on the version of Outlook that you are using. Here are the default locations of the ScanPST.exe tool for some common versions of Outlook:

  1. Outlook 2019: C:\Program Files (x86)\Microsoft Office\root\Office16
  2. Outlook 2016: C:\Program Files (x86)\Microsoft Office\root\Office16
  3. Outlook 2013: C:\Program Files (x86)\Microsoft Office\Office15
  4. Outlook 2010: C:\Program Files (x86)\Microsoft Office\Office14
  5. Outlook 2007: C:\Program Files (x86)\Microsoft Office\Office12

Please note that if you use a 64-bit version of Windows, the ScanPST.exe tool may be in the Program Files folder instead of the Program Files (x86) folder.

ScanPST to Repair Corrupted PST file

  • Double-click on the exe file to open it.
  • In the Enter the name of the file you want to scan field, enter the path, and file name of the OST file that you want to repair.

Note: You can click on the Browse button to locate the file if you’re not sure of its location.

  • Click on the Start button to begin the scan.
  • If errors are found, click on the Repair button to begin the repair process.
  • Once the repair is complete, open Outlook and check if the sync issue has been resolved.

Note: It’s important to note that the repair process may take some time, and you may need to repeat it several times to resolve the issue fully.


If the ScanPST.exe tool cannot repair your corrupt PST file or if you’re facing other issues with the tool, you may need to use a professional repair tool to fix the problem. One such tool is the SFWare PST Repair Tool, designed to repair corrupt PST and OST files effectively. Below, we discuss how to repair corrupt OST files using the SFWare PST Repair Tool.

Free Download for Windows

Steps To Repair Corrupt PST Files Using SFWare PST Repair Tool

  • Download and install the SFWare PST Repair Tool on your computer.
  • Launch the software and select an option from the screen,
    • Open PST File – If you know the location of the file.
    • Find PST File – To search for the Outlook data files.
    • Select Outlook Profile – If you want to repair multiple files.

Repair corrupt PST files using SFWare PST Repair Tool to fix outlook sync issues

  • Browse and select the corrupt OST file that you want to repair and click Next.

Select the problematic PST file that was causing the Outlook not syncing error

  • Choose the scanning method you want to use –
    • Normal Scan – For a low level of corruption.
    • Smart Scan – When the Normal Scan is not enough.
  • Select the location where you want to save the repaired OST file.
  • Click on the Repair button to begin the repair process.

SFWare PST Repair tool - Scan Options

  • Once the repair process is complete, preview the repaired OST file to ensure all data is restored.
  • Save the repaired OST file to the desired location.

Note: Make sure to activate the software to save the repaired files.

Solution 10: Fixing Outlook not syncing Issue By Repairing Corrupt OST Files 

If you’re experiencing sync issues in Outlook, it may be due to a corrupt OST (Offline Outlook Data File) file. The OST file allows you to access your email and other data offline and syncs with the server when you go online again. A corrupt OST file can cause sync issues, but fortunately, this issue can be fixed by converting the corrupt OST file to a healthy PST file using a specialized OST file converter tool.

SFWare OST to PST Converter Tool is one such tool that can help any Outlook user convert corrupt, damaged, or problematic OST files to brand-new and healthy PST files in just a few simple clicks. 

Solution 11: Repair Outlook Application Profile To Fix Outlook Sync Issue

If none of the solutions mentioned above have helped you fix the not syncing Outlook issue. Then, there’s a high chance that your Outlook application might have gotten severely corrupt. 

Thankfully, Microsoft has a free built-in Microsoft Office Repair tool that can fix issues and errors that might prevent one from using Outlook. 

Steps to Repair Outlook to resolve Microsoft Office, not Syncing Issue

  • Run the Control Panel utility and locate and click on the Programs and Features option.
  • Locate the Microsoft Office installation—Right-click on the Office entry and click on the Change option.
  • Choose the Quick Repair option and click the Repair button to start the repair process. 

If the Quick Repair doesn’t fix the Outlook not syncing issue, you can try the Online Repair option (which requires an internet connection).

  • Follow the instructions mentioned on-screen instructions to finish the repair process.

That’s it; you have safely resolved the Outlook not syncing error after following the abovementioned solution (s). 


Experiencing sync issues with your Outlook can be a frustrating experience that can negatively impact your productivity. However, diagnosing and fixing these issues is possible so that you can get back to using Outlook without any problems. We have explored some of the most common causes of Outlook sync issues and discussed some methods you can use to fix them.

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