Wordfence firewall rule update problem

Hi Guys

On one of my sites I constantly get this error. This site was working fine for ages. Dismissing the message does nothing and manually refreshing also does nothing. I get an fatal php error in the debug log:

Uncaught Error: Call to undefined function curl_exec()
Stack trace: 0 /wp-content/plugins/wordfence/vendor/wordfence/wf-waf/src/lib/http.php(70): wfWAFHTTPTransportCurl->send() 1 /wp-content/plugins/wordfence/vendor/wordfence/wf-waf/src/lib/http.php(38): wfWAFHTTP->send() 2 /wp-content/plugins/wordfence/vendor/wordfence/wf-waf/src/lib/waf.php(1944): wfWAFHTTP::get() 3 /wp-content/plugins/wordfence/lib/wordfenceClass.php(7833): wfWAFCronFetchRulesEvent->fire() 4 /wp-content/plugins/wordfence/lib/wordfenceClass.php(1573): wordfence::ajax_updateWAFRules_callback() 5 /wp-includes/class-wp-hook.php(324): wordfence::ajaxReceiver() 6 /wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters() 7 /wp-includes/plugin.php(517): WP_Hook->do_action() 8 /wp-admin/admin-ajax.php(192): do_action() 9 {main} thrown in /wp-content/plugins/wordfence/vendor/wordfence/wf-waf/src/lib/http.php on line 360

Plugin: Wordfence Security
File: /wp-content/plugins/wordfence/vendor/wordfence/wf-waf/src/lib/http.php
Line: 360

Any ideas of what I could try?

“The last rules update for the Wordfence Web Application Firewall was unsuccessful. The last successful update check was 24.10.2024 9:34, so this site may be missing new rules added since then. You may wait for the next automatic attempt at 07.11.2024 15:03 or try to Manually Update by clicking the “Manually Refresh Rules” button below the Rules list.”