diff --git a/src/wp-includes/media.php b/src/wp-includes/media.php
index 5d95b0a188596..bb3fda7af0961 100644
--- a/src/wp-includes/media.php
+++ b/src/wp-includes/media.php
@@ -5298,12 +5298,17 @@ function get_post_galleries( $post, $html = true ) {
 			// New Gallery block format as an array.
 			if ( $has_inner_blocks ) {
 				$attrs = wp_list_pluck( $block['innerBlocks'], 'attrs' );
-				$ids   = wp_list_pluck( $attrs, 'id' );
 
-				foreach ( $ids as $id ) {
-					$url = wp_get_attachment_url( $id );
+				$ids = array();
+				foreach ( $attrs as $attr ) {
+					if ( ! isset( $attr['id'] ) ) {
+						continue;
+					}
 
-					if ( is_string( $url ) && ! in_array( $url, $srcs, true ) ) {
+					$ids[] = $attr['id'];
+					$url   = wp_get_attachment_url( $attr['id'] );
+
+					if ( $url && ! in_array( $url, $srcs, true ) ) {
 						$srcs[] = $url;
 					}
 				}