diff --git a/src/wp-includes/class-wp-xmlrpc-server.php b/src/wp-includes/class-wp-xmlrpc-server.php
index 1a16d8cbf3..7bc370e31a 100644
--- a/src/wp-includes/class-wp-xmlrpc-server.php
+++ b/src/wp-includes/class-wp-xmlrpc-server.php
@@ -3553,8 +3553,14 @@ class wp_xmlrpc_server extends IXR_Server {
 			return new IXR_Error( 403, __( 'Sorry, comments are closed for this item.' ) );
 		}
 
-		$comment = array();
-		$comment['comment_post_ID'] = $post_id;
+		if ( empty( $content_struct['content'] ) ) {
+			return new IXR_Error( 403, __( 'Comment is required.' ) );
+		}
+
+		$comment = array(
+			'comment_post_ID' => $post_id,
+			'comment_content' => $content_struct['content'],
+		);
 
 		if ( $logged_in ) {
 			$display_name = $user->display_name;
@@ -3590,12 +3596,17 @@ class wp_xmlrpc_server extends IXR_Server {
 
 		$comment['comment_parent'] = isset($content_struct['comment_parent']) ? absint($content_struct['comment_parent']) : 0;
 
-		$comment['comment_content'] =  isset($content_struct['content']) ? $content_struct['content'] : null;
-
 		/** This action is documented in wp-includes/class-wp-xmlrpc-server.php */
 		do_action( 'xmlrpc_call', 'wp.newComment' );
 
-		$comment_ID = wp_new_comment( $comment );
+		$comment_ID = wp_new_comment( $comment, true );
+		if ( is_wp_error( $comment_ID ) ) {
+			return new IXR_Error( 403, $comment_ID->get_error_message() );
+		}
+
+		if ( ! $comment_ID ) {
+			return new IXR_Error( 403, __( 'An unknown error occurred' ) );
+		}
 
 		/**
 		 * Fires after a new comment has been successfully created via XML-RPC.
diff --git a/tests/phpunit/tests/xmlrpc/wp/newComment.php b/tests/phpunit/tests/xmlrpc/wp/newComment.php
index 2347f0bd1b..80e70ef32e 100644
--- a/tests/phpunit/tests/xmlrpc/wp/newComment.php
+++ b/tests/phpunit/tests/xmlrpc/wp/newComment.php
@@ -4,6 +4,30 @@
  * @group xmlrpc
  */
 class Tests_XMLRPC_wp_newComment extends WP_XMLRPC_UnitTestCase {
+
+	function test_valid_comment() {
+		$this->make_user_by_role( 'administrator' );
+		$post = self::factory()->post->create_and_get();
+ 
+		$result = $this->myxmlrpcserver->wp_newComment( array( 1, 'administrator', 'administrator', $post->ID, array(
+			'content' => rand_str( 100 )
+		) ) );
+ 
+		$this->assertNotInstanceOf( 'IXR_Error', $result );
+	}
+ 
+	function test_empty_comment() {
+		$this->make_user_by_role( 'administrator' );
+		$post = self::factory()->post->create_and_get();
+ 
+		$result = $this->myxmlrpcserver->wp_newComment( array( 1, 'administrator', 'administrator', $post->ID, array(
+			'content' => ''
+		) ) );
+ 
+		$this->assertInstanceOf( 'IXR_Error', $result );
+		$this->assertEquals( 403, $result->code );
+	}
+
 	function test_new_comment_post_closed() {
 		$this->make_user_by_role( 'administrator' );
 		$post = self::factory()->post->create_and_get( array(
@@ -19,4 +43,24 @@ class Tests_XMLRPC_wp_newComment extends WP_XMLRPC_UnitTestCase {
 		$this->assertInstanceOf( 'IXR_Error', $result );
 		$this->assertEquals( 403, $result->code );
 	}
-}
\ No newline at end of file
+
+	function test_new_comment_duplicated() {
+		$this->make_user_by_role( 'administrator' );
+		$post = self::factory()->post->create_and_get();
+
+		$comment_args = array( 1, 'administrator', 'administrator', $post->ID, array(
+			'content' => rand_str( 100 ),
+		) );
+
+		// First time it's a valid comment
+		$result = $this->myxmlrpcserver->wp_newComment( $comment_args  );
+		$this->assertNotInstanceOf( 'IXR_Error', $result );
+
+		// Run second time for duplication error
+		$result = $this->myxmlrpcserver->wp_newComment( $comment_args );
+
+		$this->assertInstanceOf( 'IXR_Error', $result );
+		$this->assertEquals( 403, $result->code );
+	}
+
+}