There are FOUR areas where reCaptcha is configured in Joomla/K2 installation ... most everyone has been only adjusting the settings from THREE areas, the last setting is sooooo tucked away many of us missed it.
Here is a revised set of instructions for getting reCaptcha to work with Joomla and K2 ...
- Goto www.google.com/recaptcha and get your Public Key and Private Keys.
- Goto Joomla Admin > Plug-in Manager > Captcha - ReCaptcha and enter your Keys and ENABLE Plug-in.
- Goto Joomla Admin > Global Configuration > Default Captcha and set it to use "Captcha - ReCaptcha".
- Goto Joomla Admin > Components > K2 > Parameters > Comments > Anti-spam protection and set it to use "Google reCaptcha" (or Both), plus ENABLE "reCaptcha for registered users".
- Goto Joomla Admin > Components > K2 > Parameters > Advanced > down to "Anti-spam Settings" and enter your Keys again, plus set "Enable reCaptcha on registration form" to YES.
Many of us have done those steps several times trying to figure out the right combination, however there is one final step, mentioned earlier in the forum, a conflict with the default reCaptcha in Joomla vs. K2. The answer to get it to work is this ...
- Goto Joomla Admin > User Manager > Options (button) > Captcha and set it to use "NONE". This will turn-off the default user registration reCaptcha loading in the background behind K2 and causing the conflict.
Edit plugins/captcha/recaptcha/recaptcha.php and change URL
Line 24: const RECAPTCHA_API_SERVER = "api.recaptcha.net/recaptcha/api";
Edit components/com_k2/views/item/view.html.php and change URL
Line 168: change URL to "api.recaptcha.net/recaptcha/api/js/recaptcha_ajax.js"
Done! Working for me now!