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Plant SCADA

Troubleshooting an Online Upgrade

  • Last UpdatedJul 30, 2026
  • 2 minute read

This section lists common issues you might encounter during your Online Upgrade, which may be related to runtime issues and redundancy connectivity.

Redundant servers do not communicate

I cannot make my redundant servers communicate and I keep getting the hardware alarm "Redundant Server not found".

  1. Check that you have set your [LAN]EarliestLegacyVersion parameter correctly.

    • If upgrading v2023 use [LAN]EarliestLegacyVersion=8400.

    • If upgrading v2023 R2 use [LAN]EarliestLegacyVersion=8500.

  2. Check that you have run the Setup Wizard and set both servers to Networked mode.

  3. Set the same server password on both servers in the Setup Wizard.

  4. If security is enabled, check that Plant SCADA Runtime Manager is running as a Windows service.

  5. Check that the Accept encrypted and non-encrypted connections (mixed mode) option is selected in Configurator (Plant SCADA | Encryption page).

    Note: The current version should not have encryption enabled with Accept encrypted and non-encrypted not selected, otherwise the servers will not be able to communicate. Mixed Mode should be used, or encryption should be disabled.

My system is performing slowly even though hardware and software requirements are met

Check your system’s power options: Control Panel, Power Options.

Embedded Image (65% Scaling) (LIVE)

Remove Upgrade related parameters

After finalizing the upgrade process and confirming that runtime is fully functional, we recommend removing or updating the following .INI parameters. You will need to restart the servers after changing the parameters for the changes to take effect.

  • [Debug]Kernel = 0: this is to enhance security and keep operators out of the kernel.

  • [LAN]EarliestLegacyVersion: remove this parameter.

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