How to Fix “Cannot Expand the folder” Error in Outlook OST file?

Summary:- The most common error Outlook are facing nowadays with Outlook PST and OST files is “Cannot Expand the folder“. If you are also a person who facing the same error, then this blog is for you. Here we are going to discuss the topic of “How to Fix “Cannot Expand the folder” Error in Outlook OST file?

One of the best features of Microsoft Outlook offers is using Exchange Server and configuring email account with IMAP settings. In both settings (IMAP & Exchange) Outlook creates OST file for enabling users to work in Offline mode. But many times user faces various unwanted errors while using these Offline OST files. One of the most popular Outlook OST is “Cannot Expand the folder. The set of folders cannot be open”.

What is the reason behind this Unable to Expand the Folder error?

  • Folder “Visible”setting is not enable
  • Improper Outlook profile configuration
  • Issue with Microsoft Outlook Application
  • Problem with Third Party Add-ins
  • PST/OST file corruption

These are some of the reasons by which users face Cannot Expand the folder error in Outlook. Now let’s check out the solution to resolve this error simply to again use Outlook with no errors.

How to Fix “Cannot Expand the Folder” Outlook OST file error manually?

Solution 1: Enable the folder “Visible” option in Outlook

Enable the ‘Folder Visible‘ option for a mailbox to fix the error message “Cannot Expand the Folder”. Want to know how to activate this possibility to fix the OST file’s error? Then follow the steps given below:-

  • Open Outlook, then simply right-click on the Mailbox in the list of folders.
  • Select properties from the menu.
  • Then, on the permissions tab box, select the Folder Visible option.
  • In the final steps simply click on Ok.

Solution 2: Disable Third Party Add-ins in Outlook

Sometimes third-party add-ins can affect mailbox synchronizing as well as the application’s functionality. You can try disabling the Outlook add-ins and then try to expand folders using. To do this simply follow the steps below:-

  • Click File > Info > Options from the Microsoft Outlook application screen.
  • Click Add-ins on the Outlook Options window. Navigate to the right panel and select the Go option (you will see it in front of Manage > COM Add-ins.)
  • Uncheck the Add-ins box and click OK.
  • Restart Microsoft Outlook and then try to Expand folders once again.

Solution 3: Repair the Outlook application

  • Select Programs and Features from the Control Panel menu.
  • Right-click on the Microsoft Office software that has been installed. From the drop-down menu, select the Change option.
  • To proceed, click on Yes.
  • Select Quick Repair as the repair option and then click Repair.
  • Complete the repair process
  • Now again open Outlook and try to open folders application.

Solution 4: Repair Corrupt Outlook Data file OST/PST

In most cases, the main reasons behind every Outlook Error error in the Outlook data file (PST/OST). To fix minor corruption errors from PST/OST files Outlook offers an inbuilt utility called scanPST.exe and Inbox Repair Tool. But it has some limitations. You can only use it to repair small OST files with a size limit of 2GB. But seeing this we at eSoftTools has launched the best way to repair highly corrupted OST/PST files known as the eSoftTools OST Recovery Software.


The has the ability to do the repairing task of OST/PST files in a much reliable manner. Also, users can also use the software to open the data file that shows “Cannot Expand the Folder” in Outlook with ease.

Steps to repair PST file with eSoftTools OST Recovery Tool:-

  • Launch The OST PST Tool on windows computer.
Welcome screen of ost database recovery
  • Add corrupt OST files (also you can add and reapir PST files).
  • Start scanning process to repair OST file errors and load all mailbox folders and items.
OST file recovery
  • Expand all mailbox folder of OST and see live preview of its inner components.
OST Mailbox Conversion Preview
  • Select Required folders and choose file type from the provided conversion options.
Export OST
  • browse and select the desired location to save resulted files and click on Convert to start the conversion process.


We have explained how to resolve the issue of “Cannot expand the folder error of OST file” in this article. We’ve outlined the most effective technique for resolving the problem here. To fix the unable to expand the folder error in an OST file, you can these approaches to get instant results. 

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