To generate a Site Key and a Secret Key, please follow the steps:
To check how the reCaptcha works, please, follow the steps:
1. Open the page where reCapthca should be; 2. Open browser console (Shift+Ctrl+I); 3. Open Console settings:
4. Uncheck 'Select Automatically' and choose any kind of browser or device; 5. Fill in and submit the form.
However, Google uses its own criteria to define whether a real man or a spam-bot is trying to send you a message. One of this criteria is the user agent. ReCapthca shows the verification pictures only if it suspects a bot.
This error message is related to the default Magento or third-party captcha. When you use a custom theme, it hides "I'm not a robot" checkbox and it's not available for submitting. Therefore, ''Incorrect CAPTCHA'' message is displayed.
The solution is pretty easy: just disable the default Magento or third-party captcha. The ''Incorrect CAPTCHA'' message should be gone. If it still appears, please do not hesitate to create a support ticket.
Having submitted the form and when the badge of Google Invisible reCaptcha appears, one may not be redirected to the successful page as there is a possibility of a third-party CAPTCHA working on the same page.
Google Invisible reCaptcha is not added to checkout pages anymore. According to the best shopping practices it is not recommended to place reCaptcha on checkout pages as it may prevent customers from placing an order and, as a result, a customer will leave items in the cart without making the purchase.