https://github.com/ethereum/go-ethereum/issues/15182

@robert-zaremba You can still use dev with datadir. Dev just uses a 0-period clique chain.

That said, –dev was not meant to be used on custom networks / genesis blocks. If you need a custom setup, you can init a chain of your choosing. Dev will try to be smart and configure a lot of stuff for easy testing, but it’s not flexible, it’s easy.

翻譯：

--dev不能用在 custom networks 和genesis blocks.

=========== Error understand ============
--dev  => 1337

So  use –dev  must networkid & chainId     set 1337