The error message in wordpress is:
Wordfence could not get an API key from the Wordfence scanning servers when it activated. You can try to fix this by going to the Wordfence “options” page and hitting “Save Changes”. This will cause Wordfence to retry fetching an API key for you. If you keep seeing this error it usually means your WordPress server can’t connect to our scanning servers. You can try asking your WordPress host to allow your WordPress server to connect to noc1.wordfence.com.
Try this found in this thread: Scroll to the bottom of the Wordfence “options” page. Check the box to remove Wordfence data on deactivation. Deactivate and reactivate the plugin. Then try your scan again and let me know if it works.