Ticket #58405: 58405.diff

src/wp-includes/class-wp-theme.php

@@ -363 +363 @@
                         $theme_path     = $this->theme_root . '/' . $this->stylesheet;
 
                         if (
-                                ! file_exists( $theme_path . '/templates/index.html' )
-                                && ! file_exists( $theme_path . '/block-templates/index.html' ) // Deprecated path support since 5.9.0.
+                                ! $this->is_block_theme()
                                 && ! file_exists( $theme_path . '/index.php' )
                         ) {
                                 $error_message = sprintf(