Altaro Dealing with “Windows Error 64” and “Windows Error 59”


The backup fails with a one of the following errors:

  • “Windows Error 64: The specified network name is no longer available.”
  • “Windows Error 59: An unexpected network error occurred.”


There’s a number of reasons that can very easily cause networks issues which will result in a failed backup pointing to a Windows Error 64 or 59. Mainly it could be down to potential hardware failures/issues or even configuration of network devices for that matter.

Aside from that, firewalls, other traffic on the line or other software could be causing load on the network or even on the storage device itself, that might be going over timeouts or maximum retransmission limits.

Sending backups over an unreliable connection such as a VPN/WAN connection can also result in such a failure, unless using the Altaro Offsite Server tool for offsite copies.

Timeouts from specific NAS boxes when using domain credentials can also be causing such disconnections.


There are numerous, distinct solutions applicable for backups failing with this error, seeing as it could be occurring for a number of reasons.

  • If you’re using a NAS as a backup location, it’s recommended that you utilise the credentials of the NAS box itself, even if it’s connected to Active Directory. The reason behind this, being that certain NAS’s have a timeout period associated for connections connected via domain credentials, so it could be the cause for the backup failure.
  • In addition to that this also doubles as a security measure in order to protect against Crypto-malware.
  • Another point to keep in mind if you’re using a NAS box, is to check whether the particular model you’re using has a sleep/standby option that could be causing such backup failure.
  • If you have other storage media available, try taking backups to this location, as the previous location may be experiencing hardware or software issues that may only present themselves during backup times. This will serve as a definite confirmation if the issue is with the previously configured location as well as a temporary solution.
  • If the backup location you have configured is going over an unreliable network, such a VPN/WAN connection, please note that this is not supported. This would only be supported if you’re making use of the Altaro Offsite Server which is only applicable for offsite copies and not primary backups.
  • If you’re using a backup device, such as a NAS which supports connections via iSCSI it’s recommended to set up the backup location this way. Devices connected via iSCSI usually perform better and in turn offer increased performance.
  • If the backup device is connected to a different switch to the backup server then it’s best to connect it to the same switch and re-test.
  • It’s recommended to change the network cables that the backup device and the backup server are connected with; additionally changing the ports on the switch would also be suggested.
  • Make sure Opportunity Locks (Oplocks) are disabled if the backup location is a NAS
  • If your backup location is a Windows machine, the equivalent to Oplocks is: Set-SmbServerConfiguration -EnableLeasing 0

    Run the above command via Powershell.
  • It’s also a good idea to reboot the backup device as well as the backup server to clear any open connections and refresh the devices.

    DWORD: SessTimeoutThe value entered here should be in seconds. You can try entering a value of 300 seconds (5 minutes) or 600 seconds (10 minutes). The default for this is 1 minute.
    This will increase the time the backup server waits for a response before the connection is aborted.

    DWORD: TcpMaxDataRetransmissions
    The value entered here will reflect the number of retries. The default number for this is 5.This will increase the number of tries the TCP retransmission mechanism will attempt to transmit data before the connection is aborted.
  • If the above does not help and you’re still experiencing issues, it’s recommended to temporarily disable any firewalls and antivirus products on the backup server, the hosts and the backup device. This applies for both software and hardware firewalls.

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