This error is resolved in the latest version of NetCommunity. Download and install the latest patch which contains all fixes from previous patches. If you are running an older version, download and install the latest version and then the patch.
Install the Blackbaud NetCommunity PluginService to the main BBNC Web server. When completed, ensure the PluginService URL is updated in the plug-in settings for both The Education Edge and The Raiser's Edge.