diff --git a/config-dist.php b/config-dist.php
index 3febb696075..333b09db9a8 100644
--- a/config-dist.php
+++ b/config-dist.php
@@ -317,20 +317,22 @@ $CFG->admin = 'admin';
 //   Redis session handler (requires redis server and redis extension):
 //      $CFG->session_handler_class = '\core\session\redis';
 //      $CFG->session_redis_host = '127.0.0.1';
-//      $CFG->session_redis_port = 6379;  // Optional.
-//      $CFG->session_redis_database = 0;  // Optional, default is db 0.
-//      $CFG->session_redis_auth = ''; // Optional, default is don't set one.
-//      $CFG->session_redis_prefix = ''; // Optional, default is don't set one.
-//      $CFG->session_redis_acquire_lock_timeout = 120;
-//      $CFG->session_redis_lock_expire = 7200;
-//      $CFG->session_redis_lock_retry = 100; // Optional wait between lock attempts in ms, default is 100.
-//                                            // After 5 seconds it will throttle down to once per second.
+//      $CFG->session_redis_port = 6379;                     // Optional.
+//      $CFG->session_redis_database = 0;                    // Optional, default is db 0.
+//      $CFG->session_redis_auth = '';                       // Optional, default is don't set one.
+//      $CFG->session_redis_prefix = '';                     // Optional, default is don't set one.
+//      $CFG->session_redis_acquire_lock_timeout = 120;      // Default is 2 minutes.
+//      $CFG->session_redis_acquire_lock_warn = 0;           // If set logs early warning if a lock has not been acquried.
+//      $CFG->session_redis_lock_expire = 7200;              // Optional, defaults to session timeout.
+//      $CFG->session_redis_lock_retry = 100;                // Optional wait between lock attempts in ms, default is 100.
+//                                                           // After 5 seconds it will throttle down to once per second.
+//
 //      Use the igbinary serializer instead of the php default one. Note that phpredis must be compiled with
 //      igbinary support to make the setting to work. Also, if you change the serializer you have to flush the database!
 //      $CFG->session_redis_serializer_use_igbinary = false; // Optional, default is PHP builtin serializer.
-//      $CFG->session_redis_compressor = 'none'; // Optional, possible values are:
-//                                               // 'gzip' - PHP GZip compression
-//                                               // 'zstd' - PHP Zstandard compression
+//      $CFG->session_redis_compressor = 'none';             // Optional, possible values are:
+//                                                           // 'gzip' - PHP GZip compression
+//                                                           // 'zstd' - PHP Zstandard compression
 //
 // Please be aware that when selecting Memcached for sessions that it is advised to use a dedicated
 // memcache server. The memcached extension does not provide isolated environments for individual uses.
diff --git a/lib/classes/session/redis.php b/lib/classes/session/redis.php
index be1851324b0..54a209fad3d 100644
--- a/lib/classes/session/redis.php
+++ b/lib/classes/session/redis.php
@@ -65,6 +65,8 @@ class redis extends handler {
     protected $prefix = '';
     /** @var int $acquiretimeout how long to wait for session lock in seconds */
     protected $acquiretimeout = 120;
+    /** @var int $acquirewarn how long before warning when waiting for a lock in seconds */
+    protected $acquirewarn = null;
     /** @var int $lockretry how long to wait between session lock attempts in ms */
     protected $lockretry = 100;
     /** @var int $serializer The serializer to use */
@@ -119,6 +121,10 @@ class redis extends handler {
             $this->acquiretimeout = (int)$CFG->session_redis_acquire_lock_timeout;
         }
 
+        if (isset($CFG->session_redis_acquire_lock_warn)) {
+            $this->acquirewarn = (int)$CFG->session_redis_acquire_lock_warn;
+        }
+
         if (isset($CFG->session_redis_acquire_lock_retry)) {
             $this->lockretry = (int)$CFG->session_redis_acquire_lock_retry;
         }
@@ -461,6 +467,8 @@ class redis extends handler {
 
         $whoami = "[pid {$pid}] {$hostname}:$uri";
 
+        $haswarned = false; // Have we logged a lock warning?
+
         while (!$haslock) {
 
             $haslock = $this->connection->setnx($lockkey, $whoami);
@@ -471,13 +479,22 @@ class redis extends handler {
                 return true;
             }
 
+            if (!empty($this->acquirewarn) && !$haswarned && $this->time() > $startlocktime + $this->acquirewarn) {
+                // This is a warning to better inform users.
+                $whohaslock = $this->connection->get($lockkey);
+                // phpcs:ignore
+                error_log("Warning: Cannot obtain session lock for sid: $id within $this->acquirewarn seconds but will keep trying. " .
+                    "It is likely another page ($whohaslock) has a long session lock, or the session lock was never released.");
+                $haswarned = true;
+            }
+
             if ($this->time() > $startlocktime + $this->acquiretimeout) {
                 // This is a fatal error, better inform users.
                 // It should not happen very often - all pages that need long time to execute
                 // should close session immediately after access control checks.
                 $whohaslock = $this->connection->get($lockkey);
                 // phpcs:ignore
-                error_log("Cannot obtain session lock for sid: $id within $this->acquiretimeout seconds. " .
+                error_log("Error: Cannot obtain session lock for sid: $id within $this->acquiretimeout seconds. " .
                     "It is likely another page ($whohaslock) has a long session lock, or the session lock was never released.");
                 throw new exception("Unable to obtain session lock");
             }
diff --git a/lib/upgrade.txt b/lib/upgrade.txt
index ffaaf8cc7b2..d805cda6c7f 100644
--- a/lib/upgrade.txt
+++ b/lib/upgrade.txt
@@ -227,6 +227,7 @@ defined or can't be applied.
 * A new method, force_lock_all_blocks(), has been added to the moodle_page class to allow pages to force the value of
   user_can_edit_blocks() to return false where necessary. This makes it possible to remove block editing on a page
   from ALL users, including admins, where required on pages with multi region layouts exist, such as "My courses".
+* Add an early $CFG->session_redis_acquire_lock_warn option
 
 === 3.11.4 ===
 * A new option dontforcesvgdownload has been added to the $options parameter of the send_file() function.