Troubleshooting high availability issues

Last published : Sep 30, 2026
The most common high availability issues involve the high availability feature not working at all, or working only intermittently. Following are common high availability issues, and probable causes and resolutions.
  • Issue The inability of the NetScaler appliances to pair the NetScaler appliances in a high availability setup.
    • Cause
      Network connectivity
      Resolution
      Verify that both the appliances are connected to the switch and the interfaces are enabled.
    • Cause
      Mismatch in the Password for the default Administrator account
      Resolution
      Verify that the password on both the appliances is the same.
    • Cause
      IP conflict
      Resolution
      Verify that both the appliances have unique NetScaler IP (NSIP) address. The appliances should not have the same NSIP address.
    • Cause
      Node ID mismatch
      Resolution
      Verify that the Node ID Configuration on both the appliances is unique. The appliances should not have the same Node ID configuration. Additionally, you must assign value for a Node ID between 1 and 64.
    • Cause
      Mismatch in the password of the RPC node
      Resolution
      Verify that both the nodes have the same RPC node password.
    • Cause
      An administrator has disabled the remote node
      Resolution
      Enable the remote node.
    • Cause
      The Firewall application has blocked the heartbeat packets
      Resolution
Verify that the UDP port 3003 is allowed.
  • Issue Both the appliances claim to be the primary appliance.
    • Cause
      Missing heartbeat packets between the appliances
      Resolution
      Verify that the UDP port 3003 is not blocked for communication between the appliances.
  • Issue The NetScaler appliance is not able to synchronize the configuration.
    • Cause
      A Firewall application is blocking the required port.
      Resolution
      Verify that the UDP port 3010 (or UDP port 3008 with secure synchronization) is not blocked for communication between the appliances.
    • Cause
      An administrator has disabled synchronization.
      Resolution
      Enable synchronization on the appliance that has the issue.
    • Cause
      Different NetScaler releases or builds are installed on appliances.
      Resolution
      Upgrade the appliances to the same NetScaler release or build.
  • Issue Command propagation fails between the appliances.
    • Cause
      A Firewall application is blocking the port.
      Resolution
      Verify that the UDP port 3011 (or UDP port 3009 with secure propagation) is not blocked for communication between the appliances.
    • Cause
      An administrator has disabled command propagation.
      Resolution
      Enable command propagation on the appliance that has the issue.
    • Cause
      Different NetScaler releases or builds are installed on appliances.
      Resolution
      Upgrade the appliances to the same NetScaler release or build.
  • Issue The NetScaler appliances in the high availability pair are unable to run the force failover process.
    • Cause
      The Secondary node is disabled.
      Resolution
      Enable the secondary node.
    • Cause
      The Secondary node is configured to stay secondary.
      Resolution
      Set the secondary high availability status of the secondary node to Enable from Stay Secondary.
  • Issue The secondary appliance does not receive any traffic after the failover process.
    • Cause
      The upstream router does not understand GARP messages of NetScaler appliance.
      Resolution
      Configure virtual MAC address on the secondary appliance.
Related information
High Availability