when NODE_ENV='production' getting error on request send about express HOT 2 CLOSED

Thanks for reaching out! Just a heads up, we usually use GitHub issues for bug reports and feature requests. While we'd love to help everyone, we can't offer in-depth support for individual apps here. For questions like yours, Stack Overflow, reddit, or similar forums might be your best bet.

that said, it looks like somehow the third argument to res.sendFile is not a function.

It could be a middleware you are using which behaves differently depending on NODE_ENV, but if you have application code checking node env then I'd start there.

Without seeing a reproducible example it's not possible to tell if this is a bug in express or your application code. What's happening is your sendFile is encountering an error (seems to be attempting to send a directory) and then when it attempts to invoke the callback passed to sendFile with the error it received, it sees that the callback is truthy, attempts to invoke it, but fails bc the callback is not a function.

from express.

If you provide a minimum reproducible example we can reopen to investigate.

from express.