Invalid API Route Status/Body Response

Why This Error Occurred

In one of your API routes a 204 or 304 status code was used as well as sending a response body.

This is invalid as a 204 or 304 status code dictates no response body should be present.

Send an empty body when using a 204 or 304 status code or use a different status code while sending a response body.

Before

pages/api/example.js

export default function handler(req, res) {
  res.status(204).send('invalid body')
}

After

pages/api/example.js

export default function handler(req, res) {
  res.status(204).end()
}