Fix Outlook Sync Errors

Synchronization is a built-in process in Microsoft Outlook that happens regularly whenever the PST files or OST file gets updated. That is as and when the Outlook sends and receives emails or any other folder is updated, simultaneously it even updates the Exchange Server about these changes. For example, when you edit, delete, send or receive an email in Microsoft Outlook, the changes will also be updated on the Microsoft Exchange Server.

At times, due to some reasons this process might get interrupted or your Outlook may fail to perform synchronization successfully. Depending on your email account settings, the amount of Outlook data, and several other reasons, the synchronization process may run into troubles that lead to Microsoft Outlook to hang or slow down. This, in turn, causes to Sync errors.


Glance through the steps below that help you to fix sync issues in your Microsoft Outlook

  • Find out the main reason for the Problem

Before going with any steps, first, check if the sync issues occur between your Microsoft Exchange Server (MES) mailbox and the OST (offline folder) file,  i.e. check to see whether your OST file is being synchronized or not. To perform this, follow the below steps:

Step1: Open Outlook and right-click any folder it can be your Inbox, Sent Items or Drafts etc.,

Step2: Select Properties - > click on Synchronization tab and look for Statistics for this folder

Step3: Now, check the details for

  • Last Synchronized on data (it should be the latest day, for example, today’s)
  • Server folder contains: Number of items
  • Offline folder contains: Number of items

Change Profile Settings

If the number of items in the Server folder contains section matches (is same as) with that of in the Offline folder contains section then, your Outlook folders are properly synched. If the number of items differs in both the sections then, you will have to verify the profile settings. For these just follow these steps:

  • Open Outlook -> File tab and select Account Settings
  • In Account Settings, just click Data Files
  • Now check whether the Mailbox – account name is set to default or not. If it’s not, then make it as default. After completion, just click the Email tab -> Mailbox – account name, and click Change
  • Just make sure that the box next to Use Cached Exchange Mode is selected and then click OK
  • To save all the changes just click on Close and exit the Account Settings window
  • Close and reopen Outlook

Re-synchronize Outlook folders

Now try re-synchronizing your Outlook folders. To achieve this, click on Tools tab and select Options. Then, in the Options dialog box, click on the Mail Setup tab. Then, check the box beside Send immediately when connected in the Send / Receive section and click Send / Receive tab. From the Window that appears now, verify that the option Perform an automatic Send / Receive when existing is selected. Then, just click the Close button to exit the window and then OK.

Empty Sync Issues \ Local failures folder

If you cannot at all synchronize any of the Outlook folders then, just try to empty the Sync Issues \ Local Failures folder in your Outlook. You might not usually see this folder unless you set it as visible. To make this folder display, just click the Folder List icon that is situated at the extreme bottom left-hand corner of your Outlook window. Now, under the All Outlook Items tab, you will see all the folders in the left-hand panel. Then, look for the Sync Issues folder, if you see the folder, just hit the + button and expand it to view the three sub-folders namely Conflicts, Local Failures, and Server Failures. Just empty the Sync Issues folder by selecting all the messages and removing them completely even from the Deleted Items folder also. When done, exit Outlook and reopen it.

While doing this, instead of synchronizing you lose emails then, you can click on, recover lost emails in Outlook quickly. Here, you will find the help needed.

Fix your OST file

If this fails to solve the issue then your OST file may be corrupt. To fix this, you will have to create a new OST file and try to re-synchronize all the folders. For this you have to first rename the old OST file, create a new one and then synchronize new file with the Microsoft Exchange Server mailbox. Now, all your sync issues will be fixed.

By creating the new OST file the errors might be fixed, but what about your data? You will lose your entire OST data, isn’t it? Instead, try to repair your corrupt OST file. To repair your corrupt OST file, first, download the Remo Repair Outlook PST tool and launch it. Now, specify the location of the corrupt OST that’s it, the tool will perform the entire repair process and gives you a healthy OST file, with data intact. When done, your Outlook will function properly without any errors. All your sync errors on Outlook will be fixed.

Also sometimes, your server unexpectedly terminates the connection and you receive an error message like “Outlook Error Number: 0×800ccc0f” . This generally can happen while sending/receiving an email. At such a time remember that fixing error 0x800ccc0f in Outlook is easy.

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Fix Outlook Sync Errors was last modified: March 18th, 2019 by Tony Landry

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