php – MultipartFormDataSection FormatException POST

I'm trying to go through post the data of a small form made in unity.

When I create a user employment;

public void NewAccount ()
{
    List formData = new List();
    formData.Add (new MultipartFormDataSection ("name", _newNameIntroduced.text));
    formData.Add (new MultipartFormDataSection ("password", _newContrasenaIntroducida.text));

    UnityWebRequest www = UnityWebRequest.Post (_newUserURL, formData);
    StartCoroutine (WaitForRequest (www));
}

Method which works perfectly.

The problem comes when sending the data to authenticate the user;

public void VerifyAccount ()
{
    List formData = new List();
    formData.Add (new MultipartFormDataSection ("name", _ nameIntroduced.text));
    formData.Add (new MultipartFormDataSection ("password", _ contrasenaIntroducida.text));

    UnityWebRequest www = UnityWebRequest.Post (_LoadUserURL, formData);
    Debug.Log ("1");
    StartCoroutine (WaitForRequest (www)); Debug.Log ("1.5");
}

Method WaitForRequest;

private IEnumerator WaitForRequest (UnityWebRequest postUser)
{
    Debug.Log ("2");
    yield return postUser.SendWebRequest ();
    Debug.Log (postUser.downloadHandler.text);
    if (Convert.ToInt32 (postUser.downloadHandler.text)! = 200)
    {
#if UNITY_ANDROID &&! UNITY_EDITOR
                dialog.showDialog ("Error");
#endif
        Debug.Log ("Error");
    }
    else
    {
#if UNITY_ANDROID &&! UNITY_EDITOR
                    dialog.showDialog ("Success");
#endif
        Debug.Log ("Success");
    }

}

The debug remains at 1.5 (message I print) and then spits the following error;

FormatException: Input string was not in the correct format
  System.Int32.Parse (System.String s) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/Int32.cs:629)
  System.Convert.ToInt32 (System.String value) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/Convert.cs:1270)

If to this method I enter only integer values ​​in the input the method is executed without exception, which I do not understand since NewAccount () It admits numbers and letters.