diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php
index 6b2da40eb3..1eacba38e8 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php
@@ -371,19 +371,16 @@ class WP_REST_Autosaves_Controller extends WP_REST_Revisions_Controller {
 			}
 		}
 
-		if ( ! $autosave_is_different ) {
-			return new WP_Error(
-				'rest_autosave_no_changes',
-				__( 'There is nothing to save. The autosave and the post content are the same.' ),
-				array( 'status' => 400 )
-			);
-		}
-
 		$user_id = get_current_user_id();
 
 		// Store one autosave per author. If there is already an autosave, overwrite it.
 		$old_autosave = wp_get_post_autosave( $post_id, $user_id );
 
+		if ( ! $autosave_is_different && $old_autosave ) {
+			// Nothing to save, return the existing autosave.
+			return $old_autosave->ID;
+		}
+
 		if ( $old_autosave ) {
 			$new_autosave['ID']          = $old_autosave->ID;
 			$new_autosave['post_author'] = $user_id;
diff --git a/tests/phpunit/tests/rest-api/rest-autosaves-controller.php b/tests/phpunit/tests/rest-api/rest-autosaves-controller.php
index b043b5e073..e987a5f699 100644
--- a/tests/phpunit/tests/rest-api/rest-autosaves-controller.php
+++ b/tests/phpunit/tests/rest-api/rest-autosaves-controller.php
@@ -688,22 +688,29 @@ class WP_Test_REST_Autosaves_Controller extends WP_Test_REST_Post_Type_Controlle
 			'post_status'  => 'publish',
 		);
 		$post_id   = wp_insert_post( $post_data );
-
 		wp_set_current_user( self::$editor_id );
 
+		// Make a small change create the initial autosave.
 		$autosave_data = array(
-			'post_content' => $post_data['post_content'],
+			'post_content' => 'Test post content changed',
 		);
-
-		// Create autosaves response.
-		$request = new WP_REST_Request( 'POST', '/wp/v2/posts/' . $post_id . '/autosaves' );
+		$request       = new WP_REST_Request( 'POST', '/wp/v2/posts/' . $post_id . '/autosaves' );
 		$request->add_header( 'Content-Type', 'application/json' );
 		$request->set_body( wp_json_encode( $autosave_data ) );
+		$response = rest_get_server()->dispatch( $request );
+
+		$this->assertSame( 200, $response->get_status() );
+
+		// Store the first autosave ID.
+		$autosave = $response->get_data();
+
+		// Try creating an autosave using the REST endpoint with unchanged content.
+		$request->set_body( wp_json_encode( $autosave_data ) );
 
 		$response = rest_get_server()->dispatch( $request );
 		$data     = $response->get_data();
 
-		$this->assertSame( 400, $response->get_status(), 'Response status is not 400.' );
-		$this->assertSame( 'rest_autosave_no_changes', $data['code'], 'Response "code" is not "rest_autosave_no_changes"' );
+		$this->assertSame( 200, $response->get_status() );
+		$this->assertSame( $autosave['id'], $data['id'], 'Original autosave was not returned' );
 	}
 }