diff --git a/assets/react/front/course/_lesson.js b/assets/react/front/course/_lesson.js
index 30e89d594..edc2977de 100644
--- a/assets/react/front/course/_lesson.js
+++ b/assets/react/front/course/_lesson.js
@@ -9,10 +9,18 @@ window.jQuery(document).ready($=>{
 
     $(document).on('click', '.tutor-single-course-lesson-comments button[type="submit"]', function(e){
         e.preventDefault();
+
         const {__} = wp.i18n;
         let btn = $(this);
         let form = btn.closest('form');
         let data = form.serialize();
+        let comment = form.find('textarea[name="comment"]').val();
+        
+        if ( comment.trim().length === 0 ) {
+            tutor_toast(__('Warning', 'tutor'), __('Blank comment is not allowed.', 'tutor'), 'error');
+            return;
+        }
+
         $.ajax({
             url: _tutorobject.ajaxurl,
             type: 'POST',
diff --git a/classes/Lesson.php b/classes/Lesson.php
index c2f203ddf..9940a4413 100644
--- a/classes/Lesson.php
+++ b/classes/Lesson.php
@@ -93,9 +93,10 @@ public function __construct() {
 	 */
 	public function tutor_single_course_lesson_load_more() {
 		tutor_utils()->checking_nonce();
-		if ( 'tutor_create_lesson_comment' === Input::post( 'action' ) ) {
+		$comment = Input::post( 'comment', '', Input::TYPE_KSES_POST );
+		if ( 'tutor_create_lesson_comment' === Input::post( 'action' ) && strlen( $comment ) > 0 ) {
 			$comment_data = array(
-				'comment_content' => Input::post( 'comment', '', Input::TYPE_KSES_POST ),
+				'comment_content' => $comment,
 				'comment_post_ID' => Input::post( 'comment_post_ID', 0, Input::TYPE_INT ),
 				'comment_parent'  => Input::post( 'comment_parent', 0, Input::TYPE_INT ),
 			);
@@ -563,8 +564,14 @@ public function tutor_lesson_completed_after( $content_id ) {
 	 */
 	public function reply_lesson_comment() {
 		tutor_utils()->checking_nonce();
+		$comment = Input::post( 'comment', '', Input::TYPE_KSES_POST );
+		if ( 0 === strlen( $comment ) ) {
+			wp_send_json_error();
+			return;
+		}
+
 		$comment_data = array(
-			'comment_content' => Input::post( 'comment', '', Input::TYPE_KSES_POST ),
+			'comment_content' => $comment,
 			'comment_post_ID' => Input::post( 'comment_post_ID', 0, Input::TYPE_INT ),
 			'comment_parent'  => Input::post( 'comment_parent', 0, Input::TYPE_INT ),
 		);