FileSystemWatcher Class - Excluding Directories

You probably haven't read You cannot exclude anything with Filter property. It only includes objects matching filter.

If you want exclude something, do it in events fired by FSW.

Determine if the file is a directory in your event handler, and do nothing then:

private void WatcherOnCreated(object sender, FileSystemEventArgs fileSystemEventArgs)
    if (File.GetAttributes(fileSystemEventArgs.FullPath).HasFlag(FileAttributes.Directory))
        return; //ignore directories, only process files

    //TODO: Your code handling files...