The Error 400 message appears in the Windows Event Log when BCAAA receives a connection without any data. This normally happens when there is a network probe or health check done by various network/systems/application monitoring tools.
Usually, these errors do not cause any performance issues with BCAAA or the ProxySG appliance. But if you see a large number of these errors and you know that they aren't from any valid health monitoring device then the system might potentially be under attack.
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