For years I have used a simple captcha application displaying a simple combination of letters and numbers.
All has worked fine except that my hosting company upgraded some of their servers from PHP 5.2.17 to PHP 5.4.29. The numbers now down't display and I can submit the form without filling any captcha into the text box.
On the otherhand, I have a couple of sites on different servers, (same hosting company) using PHP 5.2.17 and the captcha application works perfectly.
The code to make the captcha works uses $HTTP_SESSION_VARS and I understand it is deptrecated with newer versions of PHP so I changed to $_SESSION.
If I fill out the form and leave the captcha blank it will default to the error message and require a return to the form page to fill in the captcha. Once filled in and the form submitted, it goes to the default message.
It appears that the session variable is not passing to the page and recognized.