# `ExFPE.ArgumentError`
[🔗](https://github.com/g-andrade/ex_fpe/blob/v0.1.0/lib/ex_fpe/exceptions.ex#L103)

Raised by `ExFPE.new!/3` when a context cannot be built — an invalid key, mode,
radix, or alphabet.

The structured `:reason` is the same term `ExFPE.new/3` would return under
`{:error, reason}`.

# `t`

```elixir
@type t() :: %ExFPE.ArgumentError{__exception__: term(), reason: term()}
```

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