FileTransfer does not work with JPG

I'm trying to implement a download routine in an application. It worked normally, but when I went to see it I had only done tests with PDF. Already in images (jpg, png, ...) it does not work.

When I edited the file in notepad++ the first 2 lines contain this content:

--94a7e522-5247-467b-9550-9c381203c2d7
Content-Disposition: form-data; name="NomeImagem.jpg"; filename="NomeImagem.jpg"

In the PDF it contains the same lines but it opens normally.

Here is my implementation of file-transfer :

downloadFile(idFile: number, nameFile: string): Promise<any> {
    return new Promisse<any>((resolve, reject) => {
      const fileTransfer: FileTransferObject = this.fileTransfer.create();

      fileTransfer.download('${Config.getWs()}api/DownloadFile?id=${idFile}', '${this.file.getExternalDataDirectory}${nameFile}', {headers: {"token": Config.getToken()}})
         .then(res => resolve(res));
         .catch(error => reject(error));
    });
}

  

Does anyone know what it can be? Thank you.