diff --git a/db/install.xml b/db/install.xml
index 17dedd39..474abd48 100644
--- a/db/install.xml
+++ b/db/install.xml
@@ -55,7 +55,7 @@
-
+
diff --git a/db/upgrade.php b/db/upgrade.php
index 0eff24ae..ee126cca 100644
--- a/db/upgrade.php
+++ b/db/upgrade.php
@@ -203,7 +203,7 @@ function xmldb_customcert_upgrade($oldversion) {
if ($oldversion < 2022112802) {
// Define index to be added to customcert_issues.
$table = new xmldb_table('customcert_issues');
- $index = new xmldb_index('userid-customcertid', XMLDB_INDEX_UNIQUE, ['userid', 'customcertid']);
+ $index = new xmldb_index('userid-customcertid', XMLDB_INDEX_NOTUNIQUE, ['userid', 'customcertid']);
// Conditionally launch add index.
if (!$dbman->index_exists($table, $index)) {