HTTP clients, not just Axios, may impose their own requirements for building a valid request or have their own quirks to deal with.

In this case the error can be resolved by providing a Content-Length header with the length of the JSON request data when making the API request via Axios.

If you experience issues with a particular HTTP client, it may be helpful to compare the behavior with another client or check whether there are HTTP headers that may be required by the client.

@dan Oops! thank you so much Dan, it worked as a charm. I was fooled into leaving this header in because I tried the exact same request setup using one of these free api endpoints instead of fusionauth api and it worked with the content-type included. Thanks again

Worth re-emphasizing that this voids any warranty you might have from FusionAuth, per the license, exhibit A section 5.1.

You can't get support from FusionAuth if you modify the software.