# `Nvir.CastError`
[🔗](https://github.com/lud/nvir/blob/v0.16.3/lib/nvir/cast_error.ex#L1)

Exception defining an invalid cast. For instance with this dotenv file:

    NOT_AN_INT=some string

Calling `Nvir.env!/2` with the `:integer!` caster will raise an
`Nvir.CastError` exception.

    Nvir.env!("NOT_AN_INT", :integer!)

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