Outlook is one of the most popular email clients out there and has been around for quite some time now. However, just like everything else in the tech world, it isn’t immune to a few bugs and glitches here and there.
One rather frustrating issue you might run into while using Outlook is a popup saying ‘Cannot expand the folder’ when you’re trying to access a particular folder inside of Outlook. The issue started from Outlook 2010 and has been reported in pretty much every version of Outlook since.
In this article, we’re going over a few ways for you to resolve this error.
Folder limit
For those of you who didn’t know, Outlook as a limit of 1000 folders. If you have any more folders than this, any new folders will not expand. Note that this limit applies to Microsoft Exchange accounts only.
For Outlook 2010, 2013, 2016 and 2019 versions, users are limited to 500 folders. What’s more, the number of items in each folder can’t exceed 100,000. As stated by Microsoft, you may face severe performance issues if these limits are breached, not to mention the issue we’re trying to resolve.
Also read: How to schedule an email in Outlook?
Disable any add-ins
While add-ins can be extremely useful in Outlook, they can also cause issues or conflicts with some other features of the program.
Start Outlook in the Safe Mode and check if you can expand your folders. If you can, chances are one of your add-ins is causing the problem. We recommend disabling all add-ins and then turning them on one at a time to single out the culprit.
Turn off Cache mode
Turning off the Cache mode on Outlook may cause a drop in performance and loading speeds but can potentially resolve this issue.
Step 1: Click on File.

Step 2: Click on Account Settings followed by Account Settings…

Step 3: Double-click the email account you’re facing issues with.

Step 4: Uncheck the Use Cached Exchange Mode option. Restart Outlook and try again.
Also read: How to block emails on Outlook?
Repair your Outlook installation
Sometimes, you might have a broken Outlook install. Follow these steps to repair your installation.
Step 1: Press the Windows key and search for Outlook. Click on Uninstall from the right side pane.

Step 2; Find your version of Outlook in the list of programs. If you’ve installed the entire Microsoft Suite at once, search for that instead, click it and click the Change button.

Step 3: You’ll see two options as explained below.
- Quick Repair: This will work offline and resolve the most common issues with your Outlook Installation.
- Online Repair: As the name suggests, this option uses the internet and performs a more thorough installation repair.

We recommend trying quick repair first and then moving on to online repair if the former doesn’t solve the error.
Also read: How to add Bcc in Outlook?
Create a new Outlook profile
If the last step didn’t resolve your issue, you could also try making a new profile and trying again. We recommend taking a backup and renaming the folder you’re having issues with before following the steps below.
Step 1: Delete your profile from the local Outlook profile directory. By default, the directory is at the following location. Reboot your computer once you’ve deleted the file. A
C:\Users\[Your username here]\AppData\Local\Microsoft\Outloook

Step 2: Now open Outlook and click on File

Step 3: Click on Account Settings followed by Manage Profiles

Step 4: Under Profiles, click Show Profiles…

Step 5: Click the Add button to add an email account to the newly created profile.

Also read: What version of Outlook do I have?
Repair PST or OST file
Outlook saves your data in a .PST file if you’re using a POP or IMAP account. On the other hand, if you’re using an Exchange or Office 365 account, your data is saved in .OST file.
Depending upon which account you’re facing issues with, pick one of the following methods.
Repairing OST Files
Step 1: Press the Windows key and search for Control Panel.

Step 2: Once you’re in the Control panel, head over to User Accounts.

Step 3; Click on Mail (Microsoft Outlook) (32-bit)

Step 4: Click on Data Files…

Step 5: Select the account you’re having issues with and click on Open File Location…

Step 6: Delete the .OST file in this location, reboot your computer and try using Outlook again.

Also read: How to create a group email in Outlook?
Repairing PST files
Follow the steps mentioned below to repair PST files in Outlook.
Step 1: Press Windows key + R to open the Run prompt. If you’re using Office 2016, 2019 or 365, type the following file path and hit enter.
C:\Program Files (x86)\Microsoft Office\root\Office16
If you’re using Outlook 2013, enter this file path instead.
C:\Program Files (x86)\Microsoft Office\Office15

Step 2: Double-click the SCANPST.exe file in the directory.

Step 3: Click Browse and navigate to your PST file. The file is generally saved in the Documents folder.

Step 4: Click the Start button and wait for the repair to finish.
Also read: How to add Grammarly to Microsoft Word and Outlook?