Apache Commons Net FTP does not throw any exception on wrong credentials

I just managed to upload some files to an FTP server using Apache Commons Net FTP. When I use everything as it should be it works fine, I mean, the file uploading is working, but when I use, for example, a wrong password for the FTP account, obviously the files don't get uploaded to the server, but I don't get an error message either. In other words: I don't know how to show the error. I tried to show with a toast the e.getMessage() from the Exception but nothing is shown. Is there any documentation that would help me? Or am I missing something you could help me with? thank you!

This is my code:

@Override
protected Void doInBackground(Void... voids) {
    FTPClient ftpClient=new FTPClient();
    try {
        ftpClient.connect(fserver);
        ftpClient.login(fusername,fpassword);
        ftpClient.enterLocalPassiveMode();

        dirArch = new ArrayList<>();
        for (int k=0;k<adapter.getSelected().size();k++){
            dirArch.add(adapter.getSelected().get(k).getArch());
        }
        for (String archTXT : dirArch){
            File fileX =new File(stringFolder,archTXT);
            InputStream inputStream=new FileInputStream(fileX);
            ftpClient.storeFile(archTXT,inputStream);
            inputStream.close();
            pbPorc=pbPorc+pbSum;
            pb1.setProgress(pbPorc);
            pb2.setProgress(pbPorc);
        }
        ftpClient.logout();
        ftpClient.disconnect();
    } catch (IOException e) {
        e.printStackTrace();
        Toast.makeText(ExportTracks.this,e.getMessage(),Toast.LENGTH_LONG).show();
    }
    return null;
}