# `ExGram.FSM.TransitionError`
[🔗](https://github.com/rockneurotiko/ex_gram_fsm/blob/v0.1.0/lib/ex_gram/fsm/transition_error.ex#L1)

Exception raised when an invalid FSM transition is attempted and the
`on_invalid_transition` policy is `:raise` (the default).

## Fields

- `message` - human-readable error message
- `from` - the source state atom
- `to` - the attempted target state atom

## Example

    # When :raise policy is active:
    transition(context, :confirm)
    # => raises %ExGram.FSM.TransitionError{from: :idle, to: :confirm, ...}

## Handling in the bot

    def handle_error(%ExGram.Error{error: %ExGram.FSM.TransitionError{from: from, to: to}}) do
      Logger.error("Invalid FSM transition: #{from} -> #{to}")
    end

---

*Consult [api-reference.md](api-reference.md) for complete listing*