Backup fails with "0xe0009b64 - The user account that is contained in the specified logon account is disabled".

This happens if the account being used by Backup Exec is disabled.

To resolve the issue enable the service account used by Backup Exec.

For permissions required by Backup Exec, please refer to document:

Understanding Backup Exec Logon Accounts and required User Rights Assignment to resolve connection, backup or restore failures

The backup fails with the following error: Final error: 0xe0009b64 - The user account that is contained in the specified logon account is disabled. Enable the user account, or choose another logon account that contains an active user account with the appropriate privileges for the selected resource.
Final error category: Security Errors
For additional information regarding this error refer to link V-79-57344-39780