diff --git a/db/install.xml b/db/install.xml
index 41bebef..98af795 100644
--- a/db/install.xml
+++ b/db/install.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<XMLDB PATH="local/treestudyplan/db" VERSION="20230809" COMMENT="XMLDB file for Moodle local/treestudyplan"
+<XMLDB PATH="local/treestudyplan/db" VERSION="20230821" COMMENT="XMLDB file for Moodle local/treestudyplan"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="../../../lib/xmldb/xmldb.xsd"
 >
@@ -62,7 +62,6 @@
     <TABLE NAME="local_treestudyplan_line" COMMENT="Table">
       <FIELDS>
         <FIELD NAME="id" TYPE="int" LENGTH="18" NOTNULL="true" SEQUENCE="true"/>
-        <FIELD NAME="studyplan_id" TYPE="int" LENGTH="18" NOTNULL="true" SEQUENCE="false"/>
         <FIELD NAME="page_id" TYPE="int" LENGTH="20" NOTNULL="true" SEQUENCE="false"/>
         <FIELD NAME="name" TYPE="text" NOTNULL="false" SEQUENCE="false"/>
         <FIELD NAME="shortname" TYPE="text" NOTNULL="false" SEQUENCE="false"/>
diff --git a/db/upgrade.php b/db/upgrade.php
index 6fd4769..c3293cd 100644
--- a/db/upgrade.php
+++ b/db/upgrade.php
@@ -455,5 +455,25 @@ function xmldb_local_treestudyplan_upgrade($oldversion) {
         // Treestudyplan savepoint reached.
         upgrade_plugin_savepoint(true, 2023080900, 'local', 'treestudyplan');
     }
+
+    if ($oldversion < 2023082100) {
+
+        // Up to version 20230821 the studyplan_id field still existed in the install.xml file
+        // Below code remedies that - even though this is a repeat of part of an earlier upgrade
+
+        // Define field studyplan_id to be dropped from local_treestudyplan_line.
+        $table = new xmldb_table('local_treestudyplan_line');
+        $field = new xmldb_field('studyplan_id');
+
+        // Conditionally launch drop field studyplan_id.
+        if ($dbman->field_exists($table, $field)) {
+            $dbman->drop_field($table, $field);
+        }
+
+        // Treestudyplan savepoint reached.
+        upgrade_plugin_savepoint(true, 2023082100, 'local', 'treestudyplan');
+    }
+
+
     return true;
 }
\ No newline at end of file
diff --git a/version.php b/version.php
index e498010..35e47c5 100644
--- a/version.php
+++ b/version.php
@@ -1,6 +1,6 @@
 <?php
 $plugin->component = 'local_treestudyplan';  // Recommended since 2.0.2 (MDL-26035). Required since 3.0 (MDL-48494)
-$plugin->version = 2023081800;  // YYYYMMDDHH (year, month, day, iteration)
+$plugin->version = 2023082100;  // YYYYMMDDHH (year, month, day, iteration)
 $plugin->requires = 2021051700; // YYYYMMDDHH (This is the release version for Moodle 3.11)
 
 $plugin->dependencies = [