diff --git a/classes/task/update_customfield_context.php b/classes/task/update_customfield_context.php
new file mode 100644
index 0000000..7560d15
--- /dev/null
+++ b/classes/task/update_customfield_context.php
@@ -0,0 +1,55 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace mod_cms\task;
+
+use core\task\adhoc_task;
+
+/**
+ * Runs customfield context update.
+ *
+ * @package    mod_cms
+ * @author     Tomo Tsuyuki <tomotsuyuki@catalyst-au.net>
+ * @copyright  2023 Catalyst IT
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class update_customfield_context extends adhoc_task {
+
+    /**
+     * Run the task.
+     *
+     * @return void
+     */
+    public function execute() {
+        global $DB;
+
+        // Collect records which have wrong contextid in the customfield data.
+        $sql = "SELECT mcd.id mcdid, mcd.contextid mcdcontextid, mc.id mcid
+                  FROM {customfield_data} mcd
+                  JOIN {customfield_field} mcf ON mcf.id = mcd.fieldid
+                  JOIN {customfield_category} mcc ON mcc.id = mcf.categoryid
+                  JOIN {course_modules} mcm ON mcm.instance = mcd.instanceid AND mcm.module = (
+                      SELECT id FROM {modules} WHERE name = 'cms'
+                  )
+                  JOIN {context} mc ON mc.instanceid = mcm.id AND contextlevel = " . CONTEXT_MODULE . "
+                 WHERE mcc.component = 'mod_cms' AND mcd.contextid != mc.id";
+        $records = $DB->get_records_sql($sql);
+        // Update records with correct contextid.
+        foreach ($records as $record) {
+            $DB->set_field('customfield_data', 'contextid', $record->mcid, ['id' => $record->mcdid]);
+        }
+    }
+}
diff --git a/db/upgrade.php b/db/upgrade.php
index 12207b1..a32986e 100644
--- a/db/upgrade.php
+++ b/db/upgrade.php
@@ -23,11 +23,13 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
+use core\task\manager;
 use mod_cms\local\lib;
 use mod_cms\local\model\cms_types;
 use mod_cms\local\model\cms;
 use mod_cms\local\datasource\fields;
 use mod_cms\local\datasource\userlist;
+use mod_cms\task\update_customfield_context;
 
 /**
  * Function to upgrade mod_cms database
@@ -342,21 +344,8 @@ function xmldb_cms_upgrade($oldversion) {
     }
 
     if ($oldversion < 2024090301) {
-        // Collect records which have wrong contextid in the customfield data.
-        $sql = "SELECT mcd.id mcdid, mcd.contextid mcdcontextid, mc.id mcid
-                  FROM {customfield_data} mcd
-                  JOIN {customfield_field} mcf ON mcf.id = mcd.fieldid
-                  JOIN {customfield_category} mcc ON mcc.id = mcf.categoryid
-                  JOIN {course_modules} mcm ON mcm.instance = mcd.instanceid AND mcm.module = (
-                      SELECT id FROM mdl_modules WHERE name = 'cms'
-                  )
-                  JOIN {context} mc ON mc.instanceid = mcm.id AND contextlevel = " . CONTEXT_MODULE . "
-                 WHERE mcc.component = 'mod_cms' AND mcd.contextid != mc.id";
-        $records = $DB->get_records_sql($sql);
-        // Update records with correct contextid.
-        foreach ($records as $record) {
-            $DB->set_field('customfield_data', 'contextid', $record->mcid, ['id' => $record->mcdid]);
-        }
+        // Add adhoc task to update contextid in customfield records.
+        manager::queue_adhoc_task(new update_customfield_context());
         upgrade_mod_savepoint(true, 2024090301, 'cms');
     }