If you get the following exception in the output window of Visual Studio;
>>------ SPCop.exe Oops, something quite went not the way we expected! For details view the logfile in the installation directory ------ >> Failed to load one or more rules from the application base directory.
Alternatively, if SPCAF client application quits the analysis with an error message or the SPCAF Ruleset Editor crashed with a similar exception. Then you might have deployed (meaning copied) a custom rule assembly into the SPCAF installation directory, which was built for an older SDK version.
Either remove the custom rule .dll or rebuild it with the same SPCAF.SDK.dll which is installed on your machine.
This issue has been resolved in version's greater than 4.1.