Archive old emails in a new Outlook data file.Empty the Deleted Items folder and remove unimportant emails and other mailbox items.

Split Outlook data file manually or by using a third-party PST splitter tool.If you’re facing the ‘can’t open Outlook window’ issue, you can try reducing the size of your data file. If your Outlook data file has become large-sized, then it can create problems with your Outlook. Outlook creates two types of data files on the local system - PST (for POP3 email accounts) and OST (for MAPI/IMAP accounts). Restart Outlook and check if the “cannot start Microsoft Outlook” issue is resolved.In the COM Add-ins window that opens, unselect all the add-ins and click OK.In the Manage menu, select COM Add-ins and click the Go button.You can disable the add-ins to fix the problem. If you are able to use Outlook without any issues in the safe mode, then it confirms that the Outlook won’t open issue is caused by add-ins.

Select your Outlook profile and click OK.

Enter Outlook /safe in the input field and press the OK button.

Launch the Run tool by pressing Windows + R keys.

You can run Outlook in safe mode to confirm if the problem is caused by add-ins. As a result, you may encounter the ‘cannot open the Outlook window’ issue. Sometimes, these add-ins interfere with Outlook. Outlook add-ins help in enhancing the user experience as they offer certain features that don’t exist in the base application. Try the following methods to resolve the ‘cannot start Microsoft Outlook’ error: 1. 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.

Cannot open my emails in outlook