[kh99]

Originally Posted by zero_ZX

When my captcha fails I get no error message.
I see that I can use this:
$userdata->error('emailmismatch');
But what would the argument be for captcha?

The parameter is a phrase variable name, so you could create a phrase or use an existing one. There's one called humanverify_image_wronganswer that says "The string you entered for the image verification did not match what was displayed.".