Notice: wp_enqueue_style was called incorrectly.

After enabling wp_debug in wp-config.php, I receive this error.

Notice: wp_enqueue_style was called incorrectly. Scripts and styles should not be registered or enqueued until the wp_enqueue_scripts, admin_enqueue_scripts, or login_enqueue_scripts hooks. Please see Debugging in WordPress for more information. (This message was added in version 3.3.) in /var/www/public_html/wp-includes/functions.php on line 3245

I’ve isolated the issue to the SweetCaptcha plugin by disabling every plugin, then immediately enabling individuals.

I solved the problem by making the following amendments to sweetcaptcha.php:

delete the line
wp_enqueue_style( ‘sweetcaptcha_Stylesheet’, plugins_url( ‘css/style.css’, __FILE__ ) ); // TODO

then, add the line you just deleted to the sweetcaptcha_init function

secondly, change the “init” hook to the “enqueue styles” hook so it looks like this

add_action(‘wp_enqueue_scripts’, ‘sweetcaptcha_init’, 10);

so, all together, it should look like:

add_action(‘wp_enqueue_scripts’, ‘sweetcaptcha_init’, 10);
function sweetcaptcha_init() {
wp_enqueue_script(‘jquery’);
wp_enqueue_script( ‘swtcptcf’, plugins_url( ‘js/swtcptcf.js’, __FILE__ ) );
wp_enqueue_style( ‘sweetcaptcha_Stylesheet’, plugins_url( ‘css/style.css’, __FILE__ ) ); // TODO
}

https://wordpress.org/plugins/sweetcaptcha-revolutionary-free-captcha-service/