V-79-57344-790 - Backup of Sharepoint 2010 consistently fails with error 'Unable to lock the Microsoft SharePoint Portal Farm'

Problem

A backup of a Sharepoint Server 2010 or Sharepoint Foundation 2010 server/farm using the Backup Exec Sharepoint agent fails with this error. That backup job does not succeed consistently.

Error Message

V-79-57344-790 - Error: Unable to lock the Microsoft SharePoint Portal Farm.  Check the option to release the lock on the SharePoint farm topology on the backup job properties for Microsoft SharePoint, and then retry the job.

Directory \ was not found, or could not be accessed.

None of the files or subdirectories contained within will be backed up.

V-79-57344-5890 - The object was not found, or could not be accessed (Share point backup).

Cause

In Sharepoint 2010 there is no 'lock' function as referenced in the error message.  The error comes from the inability of the Backup Exec Remote Agent to determine the version/status of Sharepoint resources selected for backup.  When a Sharepoint resource is backed up there are connections made between the Remote Agent and the Sharepoint SQL server registry.  If a Registry query (or Remote Registry query in the case of a multi-server Sharepoint farm) cannot be made, this error can occur.

Solution

There are two requirements to eliminate this error message:

1. The account being used for the Sharepoint backup must have rights to the registries on both the Sharepoint web server and Sharepoint SQL server.
2. A remote registry call from the Sharepoint web server to the Sharepoint SQL server must be possible for the Backup Exec Remote Agent on the Sharepoint web server. An important part of this is that the Remote Registry service must be running on the Sharepoint SQL server.
3. If the above steps fail to resolve the error, it may be caused by a missing registry entry on the Sharepoint SQL server - the registry value can be manually created on the Sharepoint SQL server to allow identification of Sharepoint resources.  See 100031193 for manual registry value creation instructions.