System.Runtime.InteropServices.COMException (0x80005000): Unknown error (0x80005000) in MAGE log file (4254420)

Migration Agent for Exchnage (MAGE) log file shows the following error:

2015-06-25 07:59:02.3758 Px10F4 Tx3 A1 C1 M1 Trace LdapHelper::FindOne. LDAP query: searchBase - 'LDAP://DOMAIN_NAME.COM/', filter - '(&(objectClass=msExchPrivateMDB))', username - 'Domain\user_name'. 
2015-06-25 07:59:02.3758 Px10F4 Tx3 A1 C1 M1 Error System.Runtime.InteropServices.COMException (0x80005000): Unknown error (0x80005000)
   at System.DirectoryServices.DirectoryEntry.Bind(Boolean throwIfFail)
   at System.DirectoryServices.DirectoryEntry.Bind()
   at System.DirectoryServices.DirectoryEntry.get_AdsObject()
   at System.DirectoryServices.DirectorySearcher.FindAll(Boolean findMoreThanOne)
   at System.DirectoryServices.DirectorySearcher.FindOne()
   at Quest.MigrationManager.Exchange.Basis.LdapHelper.FindOneEx(String searchBase, String filter)
   at Quest.MigrationManager.Exchange.Basis.LdapHelper.GetMailboxDBLDAPInfo(String mdbDN)
   at Quest.MigrationManager.Exchange.Agent.SimpleIntraorgMailboxMover.CheckAndMove(Guid userObjectGuid, String targetMailboxDBDN)
   at Quest.MigrationManager.Exchange.Agent.Jobs.DisBaseJob.MoveMailboxToRightStore()
   at Quest.MigrationManager.Exchange.Agent.Jobs.DisBaseJob.BeforeSync()
   at Quest.MigrationManager.Exchange.Agent.Jobs.DisJob.BeforeSync()
   at Quest.MigrationManager.Exchange.Agent.Jobs.DisBaseJob.RunJob()