Validate_confirmation gives gettext error

I have a signup page where I’m validating the password & password confirmation fields using the validate_confirmation function.

def changeset(model, params \\ %{}) do
    |> cast(params, @required_fields, @optional_fields)
    |> validate_confirmation(:password)
    |> validate_length(:firstName, min: 2)

If I enter mismatching passwords, I get an error no function clause matching in Gettext.dngettext/6 in the browser -

I have the latest dependencies before posting this.

What am I doing wrong?