Using a custom theme with CF7 and others on <site>, installing Math Captcha, configuring… settings page:
Warning: call_user_func() [function.call-user-func]: First argument is expected to be a valid callback in /var/www/vhosts/<site>/httpdocs/wp-admin/includes/template.php on line 1102
De-/Activating Math Captcha (as seen in support forum): No change.
Inserting CF7 Shortcode in a form, the page with the form shows:
Fatal error: Class ‘WPCF7_Shortcode’ not found in /var/www/vhosts/<sitename>/httpdocs/wp-content/plugins/wp-math-captcha/includes/math-captcha-cf7.php on line 20
“Class not found” let me think, Math Captcha does NOT support CF7 ;-)