Bad action!

A message stating: "Bad action value. Please check your request and try again. (55006)Source: Qantas (qantas.com).

I don’t know what a “bad action value” is, but I do know I don’t want to see it when I’m booking a flight. I would guess that for many people, booking a flight involves a reasonably high level of emotional engagment and perhaps stress – not the time to be displaying obscure and unhelpful messages.

The code at the end (55006) would be inoffensive it it were appended to a plain language message, but when associated with this gibberish, it adds to the perception of complexity and things gone awry.