This error may occur directly after updating The Education Edge. The BBNC Testconfig page will show that Education Edge is not available. All features of BBNC that connect with Education Edge will fail with a server error.
Exception message: Server was unable to process request. ---> Could not load file or assembly 'Blackbaud.PIA.FE7.AFNLibA, Version=18.104.22.168, Culture=neutral, PublicKeyToken=d32fc0c6276b37c8' or one of its dependencies. The system cannot find the file specified.
Reset IIS on the BBNC Web Server. The website is still looking for the previous Education Edge files. An IIS reset is good step to do after all upgrades.