
This problem can occur when the Exchange server crashes due to hardware failure or when it is decommissioned.
OST file orphaning issue: The OST file can become orphaned when Outlook 365 cannot connect to the Exchange server and is no longer able to synchronize your email data with. When the OST file becomes corrupt, you may encounter this error. Corruption in the OST file: The OST file, which stands for Offline Storage Table, stores a cached copy of your Exchange Server mailbox and is used for offline access to your email, calendar, and other data in Microsoft Outlook. Here are some of the most common factors that cause this issue: To resolve the problem you must retrieve your mailbox data from the OST file and convert the OST to PST format with a suitable third-party tool like EdbMails. The most common cause of the 'Outlook data file OST cannot be opened' error is an orphaned OST file or improper Outlook shutdown. What causes the error 'Outlook data file OST cannot be opened'? Your Outlook data file cannot be configured. Repair corrupted OST files from Outlook 365. Your mailbox has been temporarily moved on Exchange server. Fix the error Outlook inbox not updating. Fix Outlook data file cannot be accessed. Fix Outlook the set of folders cannot be opened. Fix Outlook not connecting to server error. Recover all Exchange and Outlook OST files. Set Exchange Server Impersonation rights. Connect to Office 365 as single user mailbox. Connect to Office 365 with CSV file option. CANNOT START MICROSOFT OUTLOOK CANNOT OPEN WINDOW FULL
Connect to Office 365 with full access permission.Connecting to Individual user for its migration.Using multiple user credentials with CSV file.
Connect to Hosted Exchange for its Migration.Connect individual users for Single / Specific user Migration.Connect to multiple users using CSV file.
Connect to Exchange server for multiple mailboxes migration.