diff --git a/source/script.php b/source/script.php
index 49481545..241c05d3 100644
--- a/source/script.php
+++ b/source/script.php
@@ -95,12 +95,18 @@ class Pkg_MokowaasInstallerScript
 		// Mark MokoWaaS extensions as protected (prevents disable/uninstall at framework level)
 		$this->protectExtensions();
 
+		// Save download keys before any update site manipulation
+		$savedKeys = $this->backupDownloadKeys();
+
 		// Migrate all Moko update server URLs to new format
 		$this->migrateUpdateServerUrls();
 
 		// Clean up stale/duplicate update sites
 		$this->cleanupStaleUpdateSites();
 
+		// Restore download keys that were wiped by cleanup/migration
+		$this->restoreDownloadKeys($savedKeys);
+
 		// Fix orphaned update records (extension_id=0)
 		$this->fixUpdateRecords();
 
@@ -656,6 +662,113 @@ class Pkg_MokowaasInstallerScript
 		}
 	}
 
+	/**
+	 * Backup all non-empty extra_query values from update sites.
+	 *
+	 * @return  array  Map of update_site_id => extra_query
+	 */
+	private function backupDownloadKeys(): array
+	{
+		$keys = [];
+
+		try
+		{
+			$db = Factory::getDbo();
+			$db->setQuery(
+				$db->getQuery(true)
+					->select([$db->quoteName('update_site_id'), $db->quoteName('extra_query'), $db->quoteName('location')])
+					->from($db->quoteName('#__update_sites'))
+					->where($db->quoteName('extra_query') . ' != ' . $db->quote(''))
+			);
+			$rows = $db->loadObjectList() ?: [];
+
+			foreach ($rows as $row)
+			{
+				// Key by location so we can match after IDs change
+				$keys[$row->location] = $row->extra_query;
+				$keys['id_' . $row->update_site_id] = $row->extra_query;
+			}
+
+			// Also save to file backup for the preserveDownloadKeys() runtime guard
+			$backupFile = JPATH_ADMINISTRATOR . '/cache/mokowaas_dlkeys.json';
+			$existing   = [];
+
+			if (file_exists($backupFile))
+			{
+				$existing = json_decode(file_get_contents($backupFile), true) ?: [];
+			}
+
+			foreach ($rows as $row)
+			{
+				$existing[$row->update_site_id] = $row->extra_query;
+			}
+
+			file_put_contents($backupFile, json_encode($existing, JSON_PRETTY_PRINT));
+		}
+		catch (\Throwable $e)
+		{
+			// Non-critical
+		}
+
+		return $keys;
+	}
+
+	/**
+	 * Restore download keys that were cleared by update site cleanup.
+	 *
+	 * @param   array  $savedKeys  Map from backupDownloadKeys()
+	 */
+	private function restoreDownloadKeys(array $savedKeys): void
+	{
+		if (empty($savedKeys))
+		{
+			return;
+		}
+
+		try
+		{
+			$db = Factory::getDbo();
+			$db->setQuery(
+				$db->getQuery(true)
+					->select([$db->quoteName('update_site_id'), $db->quoteName('extra_query'), $db->quoteName('location')])
+					->from($db->quoteName('#__update_sites'))
+					->where($db->quoteName('extra_query') . ' = ' . $db->quote(''))
+			);
+			$sites = $db->loadObjectList() ?: [];
+
+			$restored = 0;
+
+			foreach ($sites as $site)
+			{
+				// Try to match by location URL first, then by old ID
+				$key = $savedKeys[$site->location] ?? $savedKeys['id_' . $site->update_site_id] ?? '';
+
+				if (!empty($key))
+				{
+					$db->setQuery(
+						$db->getQuery(true)
+							->update($db->quoteName('#__update_sites'))
+							->set($db->quoteName('extra_query') . ' = ' . $db->quote($key))
+							->where($db->quoteName('update_site_id') . ' = ' . (int) $site->update_site_id)
+					)->execute();
+					$restored++;
+				}
+			}
+
+			if ($restored > 0)
+			{
+				Factory::getApplication()->enqueueMessage(
+					sprintf('Restored %d download key(s) after update site cleanup.', $restored),
+					'message'
+				);
+			}
+		}
+		catch (\Throwable $e)
+		{
+			// Non-critical
+		}
+	}
+
 	/**
 	 * Ensure the MokoWaaS update server entry stays enabled and points
 	 * to the correct dynamic endpoint with the license key attached.