1) Check that for a given plugin, the latest version available is X, and the version running is Y, where Y < X.
2) Update the plugin.
3) The plugin update process runs, and when done, an error appears, e.g.: "Error: [EFAULT] No updates available for plexmediaserver"
4) Refresh the page - the plugin has been successfully updated to version X.
The error is erroneous.