Sending a file with multipart/form-data fails

[MaxToyberman]

This is my request

 pinch.fetch(Someurl,{
            method: "POST",
            timeoutInterval: getConfig().communication_timeout,
            sslPinning: {
                cert: getCertificateName()
            },
    
            body: request ? JSON.stringify(request) : "{}",
            headers: { 'content-type': 'multipart/form-data; charset=UTF-8' }
        })

However this request fails.

Any ideas ?

Thank you