Unable to cleanup old CAPTCHAs
Recommended CAPTCHA directory to create and use: /some/server/homepages/22/123456/htdocs/joomla/captcha
Recommended CAPTCHA URL to use: http://your.domain.com/captcha
You have not correctly configured the Directory to Write Captchas settings in the module configuration advanced options.
Look at the suggestion in the error message which says Recommended CAPTCHA directory to create and use.
This is the recommended directory you will need to create using the file system tools provided by your web hosting provider.
For further information, please see this article: