[@rfk55tn Participant 9 years, 11 months ago]

I have the exact same issue. Using WP 4.6.1 with twenty sixteen theme + bbpress and no other plug-ins on a local install for testing.

I can create forums and topics. However, I cannot post any comments and keep getting the following error message: ERROR: Are you sure you wanted to do that?

Have tried repeated uninstall/install of both WP and BBP. Same result.