FileInputStream (file) returning ENOENT (no such file or directory) android

I am trying to extract a file (any type) from a file manager and encode that file to String Base64. I found many answers related to IMAGES, but I need any type of file. He is what I do.

I am pulling a file (any type) from a gallery like this

Intent intent = new Intent();
intent.setType("*/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(intent, "Choose file"), GALLERY_REQUEST_CODE);

      

        
        
        
      

    

And in my result

Uri returnUri = intent.getData();

      

        
        
        
      

    

Which gives me the content: //com.android.providers.downloads.documents/document/1646 '

Then i try

File file = new File( returnUri.getPath() );

      

        
        
        
      

    

So far so good, but then I try to encode the file to Base64 string:

    String str = null;
    try {
        str = convertFile(file);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

      

        
        
        
      

    

And the convertFile method

public String convertFile(File file)
        throws IOException {
    byte[] bytes = loadFile(file);
    byte[] encoded = Base64.encode(bytes, Base64.DEFAULT);
    String encodedString = new String(encoded);

    return encodedString;

}

      

        
        
        
      

    

And the loadFile method

private static byte[] loadFile(File file) throws IOException {
    InputStream is = new FileInputStream(file);

    long length = file.length();
    if (length > Integer.MAX_VALUE) {
        Log.i("MobileReport","Anexo -> loadfile(): File is too big!");
        // File is too large
    }
    byte[] bytes = new byte[(int)length];

    int offset = 0;
    int numRead = 0;
    while (offset < bytes.length
           && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
        offset += numRead;
    }

    if (offset < bytes.length) {
        throw new IOException("It was not possible to read the entire file "+file.getName());
    }

    is.close();
    return bytes;
}

      

        
        
        
      

    

Error in the first line of the loadFile method

InputStream is = new FileInputStream(file);

      

        
        
        
      

    

The app crashes and in the log I got:

java.io.FileNotFoundException: /document/1646: open failed: ENOENT (No such file or directory)

      

        
        
        
      

    

I declared READ and WRITE permissions. Can anyone help me with this error? Thank!