diff --git a/web/themes/asc_bootstrap/asc_bootstrap.info.yml b/web/themes/asc_bootstrap/asc_bootstrap.info.yml
index ae85d718a9d2e989e7266b0a957f067f572ac47a..9169f6ec6cb8989ccb9c6bddf424a70418b6f9a9 100755
--- a/web/themes/asc_bootstrap/asc_bootstrap.info.yml
+++ b/web/themes/asc_bootstrap/asc_bootstrap.info.yml
@@ -1,4 +1,4 @@
-core: 8.x
+core_version_requirement: ^8 || ^9
 type: theme
 base theme: bootstrap
 
diff --git a/web/themes/asc_bootstrap/asc_bootstrap.theme b/web/themes/asc_bootstrap/asc_bootstrap.theme
index 0199f7e916d8f52b78ee4f56964cafbd1b469531..e204f0a911182a975cf1c3b0103edd447b4a792b 100755
--- a/web/themes/asc_bootstrap/asc_bootstrap.theme
+++ b/web/themes/asc_bootstrap/asc_bootstrap.theme
@@ -12,7 +12,7 @@
 function asc_bootstrap_preprocess_page(&$vars, $hook) {
  // Render the library as laid out in herchel.libraries.yml
  $libraries['#attached']['library'][] = 'asc_bootstrap/asc_bootstrap-corescripts';
- drupal_render($libraries);
+ \Drupal::service('renderer')->render($libraries);
 
  //adds site name variable which is used as logo alt and title text
  $vars['site_name'] = \Drupal::config('system.site')->get('name');
diff --git a/web/themes/asc_gateway/asc_gateway.info.yml b/web/themes/asc_gateway/asc_gateway.info.yml
index a25b2b0594e2e16c0568f9ae5f83892dd04fcbe8..a83317d73d162c71ecd46b47a804aa7b48a1d881 100644
--- a/web/themes/asc_gateway/asc_gateway.info.yml
+++ b/web/themes/asc_gateway/asc_gateway.info.yml
@@ -1,4 +1,4 @@
-core: 8.x
+core_version_requirement: ^8 || ^9
 type: theme
 base theme: bootstrap
 
diff --git a/web/themes/asc_seven/asc_seven.info.yml b/web/themes/asc_seven/asc_seven.info.yml
index 8d15068c3c3ea7da3e8bc020d21645b2afe65506..3e2a58d8ea1b124dc94f3b9f6fc8c56c3acbfb71 100644
--- a/web/themes/asc_seven/asc_seven.info.yml
+++ b/web/themes/asc_seven/asc_seven.info.yml
@@ -18,7 +18,7 @@ description: 'Adds custom CSS to default administration theme for Drupal 8.'
 alt text: 'Default administration theme for Drupal 8 with simple blocks, clean lines, and custom CSS.'
 package: Core
 version: VERSION
-core: 8.x
+core_version_requirement: ^8 || ^9
 
 regions:
   header: 'Header'