Backend Error

Since some days my sites generate the following error:

Error Details
=============
An error of type E_ERROR was caused in line 1221 of the file /var/www/html/wp-content/plugins/wpvulnerability/wpvulnerability-general.php. Error message: Uncaught ValueError: version_compare(): Argument #3 ($operator) must be a valid comparison operator in /var/www/html/wp-content/plugins/wpvulnerability/wpvulnerability-general.php:1221
Stack trace:
#0 /var/www/html/wp-content/plugins/wpvulnerability/wpvulnerability-general.php(1221): version_compare('2.4.65', '', '')
#1 /var/www/html/wp-content/plugins/wpvulnerability/wpvulnerability-software.php(115): wpvulnerability_get_vulnerabilities('apache', '2.4.65', 0)
#2 /var/www/html/wp-content/plugins/wpvulnerability/wpvulnerability-software.php(146): wpvulnerability_get_fresh_vulnerabilities('apache')
#3 /var/www/html/wp-content/plugins/wpvulnerability/wpvulnerability-software.php(227): wpvulnerability_get_installed('apache')
#4 /var/www/html/wp-content/plugins/wpvulnerability/wpvulnerability-run.php(133): wpvulnerability_get_vulnerabilities_clean('apache')
#5 /var/www/html/wp-content/plugins/wpvulnerability/wpvulnerability.php(98): wpvulnerability_expired_database_data()
#6 /var/www/html/wp/wp-includes/class-wp-hook.php(324): wpvulnerability_plugin_init('')
#7 /var/www/html/wp/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)
#8 /var/www/html/wp/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#9 /var/www/html/wp/wp-settings.php(727): do_action('init')
#10 /var/www/html/wp-config.php(142): require_once('/var/www/html/w...')
#11 /var/www/html/wp/wp-load.php(55): require_once('/var/www/html/w...')
#12 /var/www/html/wp/wp-admin/admin.php(35): require_once('/var/www/html/w...')
#13 /var/www/html/wp/wp-admin/index.php(10): require_once('/var/www/html/w...')
#14 {main}
 thrown