What condition can place a switch port into the err-disabled state?

A port security violation is a common reason for a switch port to enter the err-disabled state. When port security is configured on an interface and a violation occurs (e.g., an unauthorized MAC address attempts to connect), the switch can be configured to shut down the port, placing it into err-disabled. The shutdown command manually disables the port, but it's not an error state; it's an administrative action. Nothing plugged into the port means the port is down/down, but not err-disabled. Latency is a performance issue, not a condition that directly triggers an err-disabled state on a port.