Error with fetch

Please provide the following:

  1. SDK Version: “expo”: “~38.0.8”
  2. Platforms(Android/iOS/web/all): Android/iOS

Hello, I have been trying to perform an authentication, performing a “fetch”.

I have had the following error:

Object {
“error”: “unauthorized”,
“error_description”: “Full authentication is required to access this resource”,
}

This is my code:
userLogin = () => {

     var data = new FormData();

     data.append('grant_type', 'password')

     data.append('username',this.state.username)

     data.append('password',this.state.password)

    

    const url = 'http://64.225.***.***:8080/oauth/token';

   const credentials = md5("angularapp" + ":" + "12345")

    fetch( url ,{

      method: 'POST',

      

       headers: {  

        'Authorization': 'Basic YW5ndWxhcmFwcDoxMjM0NQ==' + credentials,

        'Content-Type': 'application/x-wwww-form-urlencoded',

        'Accept': 'application/json', 

        'Accept-Encoding': 'gzip, deflate, br',

        'Connection': 'keep-alive'

    },

    body: JSON.stringify(data)

         

    })   .then((response) => response.json())

         .then((responseData) => { 

         console.log(responseData); 

                                 

    })

    .catch((err) => { console.log(err);

});

}

I did the same request in Postman and there is working.

Any ideas?

Thanks.