Complete the captcha before posting
The comment form refused to submit because comment captcha is on and the widget was not completed (client-side check before the API call).
Why this happens
Captcha on comments is enabled and keys are present, but prepareSubmit failed — unchecked box, expired widget, or blocked script. Server-side bad tokens become Captcha verification failed instead.
Diagnose and fix
1. Visitor: solve the captcha, then click Post.
2. Allow third-party captcha scripts (ad blockers often break the widget).
3. Admin: Captcha on comments + valid provider keys; or turn comment captcha off if you do not want it.
4. If keys are missing, you may see Captcha enabled but not configured instead of this prompt.