diff --git a/enrol/paypal/db/upgrade.php b/enrol/paypal/db/upgrade.php
index 5ed2ae764a5..9daab41ba38 100644
--- a/enrol/paypal/db/upgrade.php
+++ b/enrol/paypal/db/upgrade.php
@@ -43,7 +43,9 @@
 defined('MOODLE_INTERNAL') || die();
 
 function xmldb_enrol_paypal_upgrade($oldversion) {
-    global $CFG;
+    global $DB;
+
+    $dbman = $DB->get_manager();
 
     // Moodle v3.1.0 release upgrade line.
     // Put any upgrade step following this.
@@ -57,5 +59,21 @@ function xmldb_enrol_paypal_upgrade($oldversion) {
     // Automatically generated Moodle v3.4.0 release upgrade line.
     // Put any upgrade step following this.
 
+    if ($oldversion < 2017111301) {
+
+        // Define field instanceid to be added to enrol_paypal.
+        // For some reason, some Moodle instances that are upgraded from old versions do not have this field.
+        $table = new xmldb_table('enrol_paypal');
+        $field = new xmldb_field('instanceid', XMLDB_TYPE_INTEGER, '10', null, XMLDB_NOTNULL, null, '0', 'userid');
+
+        // Conditionally launch add field instanceid.
+        if (!$dbman->field_exists($table, $field)) {
+            $dbman->add_field($table, $field);
+        }
+
+        // Paypal savepoint reached.
+        upgrade_plugin_savepoint(true, 2017111301, 'enrol', 'paypal');
+    }
+
     return true;
 }
diff --git a/enrol/paypal/version.php b/enrol/paypal/version.php
index a0aad9687b9..60ae6edfcf2 100644
--- a/enrol/paypal/version.php
+++ b/enrol/paypal/version.php
@@ -25,7 +25,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version   = 2017111300;        // The current plugin version (Date: YYYYMMDDXX)
+$plugin->version   = 2017111301;        // The current plugin version (Date: YYYYMMDDXX)
 $plugin->requires  = 2017110800;        // Requires this Moodle version
 $plugin->component = 'enrol_paypal';    // Full name of the plugin (used for diagnostics)
 $plugin->cron      = 60;