diff --git a/db/migrations/5.5.14_cleanup_cw_tasks.php b/db/migrations/5.1.53_cleanup_cw_tasks.php
similarity index 92%
rename from db/migrations/5.5.14_cleanup_cw_tasks.php
rename to db/migrations/5.1.53_cleanup_cw_tasks.php
index 94ab0198946bc8c876b42431377e9fefef07e4a0..8df653d5b538733907637b9d5ca9cee7c2db7cc6 100644
--- a/db/migrations/5.5.14_cleanup_cw_tasks.php
+++ b/db/migrations/5.1.53_cleanup_cw_tasks.php
@@ -11,7 +11,7 @@ final class CleanupCwTasks extends Migration
     {
         DBManager::get()->exec('
             DELETE FROM `cw_tasks`
-            WHERE `solver_type` = "user"
+            WHERE `solver_type` = "autor"
               AND `solver_id` NOT IN (SELECT `user_id` FROM `auth_user_md5`)'
         );
         DBManager::get()->exec('
diff --git a/db/migrations/5.5.14_cleanup_cw_tasks_placeholder.php b/db/migrations/5.5.14_cleanup_cw_tasks_placeholder.php
new file mode 100644
index 0000000000000000000000000000000000000000..cba0d26ebc48123316ae7924f7cf01559c0adfd0
--- /dev/null
+++ b/db/migrations/5.5.14_cleanup_cw_tasks_placeholder.php
@@ -0,0 +1,17 @@
+<?php
+/**
+ * This migration only exists as a placeholder for the original
+ * migration 5.5.14 which has been renumbered to 5.1.53 as it was
+ * downported.
+ * As everything has already been done in 5.1.53, nothing happens here.
+ *
+ * @see https://gitlab.studip.de/studip/studip/-/issues/3669
+ */
+
+final class CleanupCwTasksPlaceholder extends Migration
+{
+    public function description()
+    {
+        return 'empty placeholder for former migration with wrong number -> see 5.1.53';
+    }
+}
diff --git a/lib/classes/UserManagement.class.php b/lib/classes/UserManagement.class.php
index 620672c641f485ae71efbaab69ae1c85907647ea..1a49aed31240f6310df5b683fe8546dde6c91e12 100644
--- a/lib/classes/UserManagement.class.php
+++ b/lib/classes/UserManagement.class.php
@@ -990,7 +990,7 @@ class UserManagement
         \Courseware\UserProgress::deleteBySQL('user_id = ?', [$this->user_data['auth_user_md5.user_id']]);
         \Courseware\Bookmark::deleteBySQL('user_id = ?', [$this->user_data['auth_user_md5.user_id']]);
         \Courseware\Task::deleteBySQL(
-            '`solver_id` = ? AND `solver_type`= "user"',
+            '`solver_id` = ? AND `solver_type`= "autor"',
             [$this->user_data['auth_user_md5.user_id']]
         );
         // delete courseware elements in courses of this user