Http post request succeeds but returns error

Ionic Framework ionic-v3
1

I am making an http post request from my iOS app built with Ionic. I can view the data on the server, so I know its working, but the console prints ‘Upload failed!’ and the following error:

{"_body":{“isTrusted”:true},“status”:0,“ok”:false,“statusText”:"",“headers”:{},“type”:3,“url”:n
ull}

Here is my code:

this.http.post(url, postParams, options)
        .subscribe(data => {
          console.log('Upload succeeded!');
          console.log(JSON.stringify(data['_body']));
          resolve(data['_body']);
        }, error => {
          console.log('Upload failed!');
          console.log(JSON.stringify(error)); // Error getting the data
          resolve(error);
        });

Why would it work, but go to the error branch of the observable (subscribe)?