Fixed Set of Folders Cannot be Opened Error in Outlook

Hi Everyone this is Prem, I have worked as Microsoft 365 support ambassador. We see a lot of ticket for “Set of Folders Cannot be Opened Error in Outlook”. In this blog I am going to share a common step which we used to suggest to end users.


The error can have different reason mentioned as well which caused the error to occur. For eg. Set of Folders Cannot be Opened, the ost file is corrupted. 


All the error starting with Set of Folders Cannot be Opened can be troubleshooted with one Generic step.


Steps to Fix Set of Folders Cannot be Opened Error in Outlook:

Close Outlook app completely.


Open file Explorer then Go to C drive then Click to open Users folder :

Fixed Set of Folders Cannot be Opened Error in Outlook

Select the user account which you have logged in with on the computer (In my case its premb):

Fixed Set of Folders Cannot be Opened Error in Outlook

Click on view and then check the box for Hidden items :