Unfortunately, Dropbox has made a system update recently that has disabled sharing of files (URLs of the past no longer work because of different address). This has disabled the ability to automatically update PLS (as well as a couple of other verification checks). Fortunately, there has not been any updates to PLS recently and you are likely on the latest version. You can always download the latest from peerlendingserver.com if not.
BTW, I have been working on a newer system with the help of another benevolent user to create the next release. We are doing this in our spare time and will likely take a while to finish. We will let everyone know when the next version is to be released.