TypeError: Invalid character in header field name about polyfiller

[wessberg]

I think what you're seeing here is simply an error related to trying to use an invalid character as part of the value for the request headers of a fetch request. The error is reported from within the polyfill bundle as the error is thrown by the fetch polyfill, but based on the provided stack trace I wouldn't suspect a bug in the fetch polyfill. By the way, I'm working on sourcemap support which will make it easier to debug this kind of stuff.

[tommedema]

Hmm ok. I'm not really passing in any special headers so perhaps this is the user's chrome extension or something?

This is my fetch call

fetch(endpoint, {
    method: 'post',
    headers: {
      "Accept": "application/json",
      "Content-type": "application/json"
    },
    body: JSON.stringify(bodyObj)
  })

[wessberg]

Sure, that can happen. Could maybe also be another library you are relying on that is sending a fetch request? In any case, what you posted here looks fine to me