Ionic downloader doesn't download mp4 file

hello guys i have a problem. i want to download video file with ionic downloader and i have a problem: 1008.

the download codes:

var req: DownloadRequest = {
      uri: url,
      title: this.makename(10) + ".mp4",
      mimeType: "video/mp4",
      visibleInDownloadsUi: true,
      notificationVisibility: NotificationVisibility.VisibleNotifyCompleted,
      destinationInExternalFilesDir: {
        dirType: 'Downloads',
        subPath: 'MyFile.apk'
      .then((location: string) => {
        this.toast.presentToast('File downloaded at:' + location)
        this.url2 = location;
      .catch((error: any) => {
        alert("err: " + error)   ///right here i got 1008 err

but not everytime i got this error. i got this error sometimes. how can i fix this?

What is this “Ionic downloader” of which you speak?

ionic downloader from official docs