What causes the error Unable to Mount Database (hr=0x80004005, ec=1108)?
An Exchange database (EDB) contains user mailboxes, emails, attachments, files and folders. However, the Exchange database can dismount from the Exchange server due to various reasons. In this situation, users are unable to access their mailboxes and the server fails to connect to the database, breaking email flow and connectivity. You can mount the Exchange database to the server manually from the Exchange admin center (EAC) or by using PowerShell cmdlets. When mounting the database, you might encounter the following error message.
“Failed to mount database “MBX-DB02-2016”. Error: An Active Manager operation failed. Error: The database action failed. Error: Operation failed with message: MapiExceptionDatabaseError: Unable to mount database. (hr=0x80004005, ec=1108) Diagnostic context: Lid: 65256 Lid: 10722 StoreEc: 0x454 Lid: 1494 — Remote Context Beg – Lid: 1235 dwParam: 0x5698 Lid: 57728 dwParam: 0x27995F Lid: 46144 dwParam: 0x569A97 Lid: 34880 dwParam: 0x569F97 Lid: 34760 StoreEc: 0x980 Lid: 42144 dwParam: 0x56A13F Lid: 34880 dwParam: 0x56A45F Lid: 54472 StoreEc: 0x1388 Lid: 42184 StoreEc: 0x454 Lid: 1750 — Remote Context End — Lid: 1047 StoreEc: 0x454 [Database: MBX-DB02-2016, Server:xyz@contoso.com]”