Outlook creates two types of data files on the local system - PST (for POP3 email accounts) and OST (for MAPI/IMAP accounts).
How to Fix “Cannot Start Microsoft Outlook” Error? This error prevents Outlook users from using the application. Cannot open the Outlook window” error is one of the prevalent errors that Outlook users face.
For instance, the “Cannot start Microsoft Outlook. However, Outlook users occasionally run into problems with the application. Microsoft Outlook is a powerful email client that offers many useful features for information management.