Getting error on saving settings

I doubt this error is related with the plugin.

I have this error as well. the debug file shows:

Uncaught Error: Call to undefined function check_admin_referer() in
/var/www/html/wp-content/plugins/http-headers/http-headers.php:629 Stack trace: #0 /var/www/html/wp-includes/class-wp-hook.php(289): http_headers_option() #1 /var/www/html/wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters() #2 /var/www/html/wp-includes/plugin.php(478): WP_Hook->do_action() #3 /var/www/html/wp-includes/option.php(434): do_action() #4 /var/www/html/wp-includes/option.php(812): update_option()

Please be honest. Multiple people are reporting the same error. When we try to save the settings we have made we get a critical error. Over and over again.

You may not know how to fix it. That’s ok. Someone else may. But refusing to acknowledge the truth people are telling you is unprofessional and unethical.

The only reason I didn’t fix this is that I can’t reproduce it. It’s simple. Nothing related with my work ethic and professionalism.

You may forget that this is a free plugin, it’s not funded by anyone and the time I spend working on it is a limited.

However, it works well on a lot of sites. This make me thought that the issue you have experience is something related with your specific installation (WP version/other WP plugins/OS/Web server/PHP version, etc.)