Error validation CAPTCHA: id of session CAPTCHA not indentified

reCAPTCHA Versión: 8.x-2.4
CAPTCHA 8.x-1.0-beta1+35-dev

Days ago i get the next error "error validation CAPTCHA: id of session CAPTCHA not indentified"
when i try create one account whith CAPTCHA and reCAPTCHA modules , normally in the past i never have this problem, is crazy because when in "admin/config/people/captcha/recaptcha" i disable the option:
"Enable fallback for browsers with JavaScript disabled"
and the problem not appear moore along some days but today the same error return, and enable again the option:
"Enable fallback for browsers with JavaScript disabled"
and the problem fix again.
Maybe is because the error is fix when clean the cache?
How i fix the problem? Thanks