Known limitation: The upgrade process does not reconfigure the keyring_file_data option, because the upgrade process does not regenerate or overwrite the current configuration (my.ini) file. The keyring plugin is new as of MySQL Server 5.7.11, and is enabled by default, but it requires a valid keyring_file_data definition. In MySQL Server 5.7.11, keyring_file_data is set to an invalid (INSTALLDIR) location on Windows. To change it, you can either manually change the setting in my.ini, or click the reconfigure link in the Installer dashboard for your MySQL Server installation to regenerate the my.ini file from scratch. The Installer sets it to "%PROGRAMDATA%/MySQL/MySQL Server 5.7/keyring/keyring".