Opening files downloaded by DownloadManager causes "The document path is not valid" error

I'm trying to open pdf file downloaded by DownloadManager but from time to time I'm getting "The document path is not valid" on Samsung Galaxy S3 with Android 4.1.2

Intent:

Intent openIntent = new Intent(Intent.ACTION_VIEW);
openIntent.setDataAndType(downloadManager.getUriForDownloadedFile(lastDownloadId), "application/pdf");
startActivity(openIntent);

Permissions:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

DownloadManager:

Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).mkdirs(); 

DownloadManager downloadManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE); 
long lastDownloadId = downloadManager.enqueue(new DownloadManager.Request(uri)
    .setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI | DownloadManager.Request.NETWORK_MOBILE)
    .setAllowedOverRoaming(false)
    .setTitle(title)
    .setDescription(description)
    .setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "myfile.pdf"));

What am I doing wrong?

Edit: From to time I'm getting this:

COLUMN_ID: 108 
COLUMN_BYTES_DOWNLOADED_SO_FAR: 33085
COLUMN_LAST_MODIFIED_TIMESTAMP: 1397152425941 
COLUMN_LOCAL_URI: null
COLUMN_STATUS: 16 COLUMN_REASON: 1008

Why?

Solution

A status of 16 is STATUS_FAILED, meaning that the download failed. A reason of 1008 is ERROR_CANNOT_RESUME, and I have no idea what that means in the real world. But, your file was not downloaded, and hence you have no Uri.