diff -u b/includes/session.inc b/includes/session.inc
--- b/includes/session.inc
+++ b/includes/session.inc
@@ -615,7 +615,7 @@
  *   The session id which may have been hashed.
  */
 function drupal_session_id($id) {
-  if (variable_get('hash_session_ids', FALSE) && !variable_get('do_not_hash_session_ids', FALSE)) {
+  if (variable_get('hashed_session_ids_supported', FALSE) && !variable_get('do_not_hash_session_ids', FALSE)) {
     $id = drupal_hash_base64($id);
   }
   return $id;
diff -u b/modules/system/system.install b/modules/system/system.install
--- b/modules/system/system.install
+++ b/modules/system/system.install
@@ -673,7 +673,7 @@
   variable_set('cron_key', $cron_key);
 
   // This variable indicates that the database is ready for hashed session ids.
-  variable_set('hash_session_ids', TRUE);
+  variable_set('hashed_session_ids_supported', TRUE);
 }
 
 /**
@@ -3408,7 +3408,7 @@
   }
 
   // This variable indicates that the database is ready for hashed session ids.
-  variable_set('hash_session_ids', TRUE);
+  variable_set('hashed_session_ids_supported', TRUE);
 }
 
 /**
diff -u b/sites/default/default.settings.php b/sites/default/default.settings.php
--- b/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
@@ -856,7 +856,7 @@
 # $conf['sa_core_2023_004_phpinfo_flags'] = ~(INFO_VARIABLES | INFO_ENVIRONMENT);
 
 /**
- * Session ids are hashed by default before being stored in the database. This
+ * Session IDs are hashed by default before being stored in the database. This
  * reduces the risk of sessions being hijacked if the database is compromised.
  *
  * This variable allows opting out of this security improvement.