OST Error 8004011D-526-80040115-0 frequently occurs in older versions of Microsoft Outlook, such as 2010, 2013, and 2016, and is typically linked to synchronization or connectivity issues with Microsoft Exchange Server.
There is a Professional method to fix this error like using Sysinfo OST Recovery Tool.
Also, there are manual methods like Updating Outlook, Restart Outlook, Check connectivity, Diable Anti-Virus, and many more. You can check out here: https://www.recoveryandmanagement.com/fix-ost-error-8004011d-526-80040115-0/

Tool: https://www.sysinfotools.com/recovery/ost-file-recovery.php