The Outlook 0x80040900 error occurs when Outlook cannot connect to the email server, blocking sending or receiving emails. To fix it, first ensure your internet connection is stable. Next, verify and correct your email server settings in Outlookâs Account Settings. If the problem persists, repairing corrupted PST files using a reliable tool like Aryson PST Recovery can restore lost emails and fix errors without data loss. Another solution is creating a new Outlook profile to avoid profile corruption issues. Additionally, repairing the Microsoft Office installation can fix damaged Outlook files causing this error. Manual fixes are helpful but may require technical knowledge and carry some risk, so using dedicated recovery software is often the safest and most effective option.
