diff --git a/enrol/manual/lib.php b/enrol/manual/lib.php
index 24e312260ad..2e052760c56 100644
--- a/enrol/manual/lib.php
+++ b/enrol/manual/lib.php
@@ -197,14 +197,14 @@ class enrol_manual_plugin extends enrol_plugin {
         global $CFG, $PAGE;
         require_once($CFG->dirroot.'/cohort/lib.php');
 
+        static $called = false;
+
         $instance = null;
-        $instances = array();
         foreach ($manager->get_enrolment_instances() as $tempinstance) {
             if ($tempinstance->enrol == 'manual') {
                 if ($instance === null) {
                     $instance = $tempinstance;
                 }
-                $instances[] = array('id' => $tempinstance->id, 'name' => $this->get_instance_name($tempinstance));
             }
         }
         if (empty($instance)) {
@@ -222,7 +222,11 @@ class enrol_manual_plugin extends enrol_plugin {
         $context = context_course::instance($instance->courseid);
         $arguments = array('contextid' => $context->id);
 
-        $PAGE->requires->js_call_amd('enrol_manual/quickenrolment', 'init', array($arguments));
+        if (!$called) {
+            $called = true;
+            // Calling the following more than once will cause unexpected results.
+            $PAGE->requires->js_call_amd('enrol_manual/quickenrolment', 'init', array($arguments));
+        }
 
         return $button;
     }
diff --git a/lib/outputcomponents.php b/lib/outputcomponents.php
index 505e04d4d85..fa9a76f5ed5 100644
--- a/lib/outputcomponents.php
+++ b/lib/outputcomponents.php
@@ -2089,12 +2089,10 @@ class html_writer {
      */
     public static function script($jscode, $url=null) {
         if ($jscode) {
-            $attributes = array('type'=>'text/javascript');
-            return self::tag('script', "\n//<![CDATA[\n$jscode\n//]]>\n", $attributes) . "\n";
+            return self::tag('script', "\n//<![CDATA[\n$jscode\n//]]>\n") . "\n";
 
         } else if ($url) {
-            $attributes = array('type'=>'text/javascript', 'src'=>$url);
-            return self::tag('script', '', $attributes) . "\n";
+            return self::tag('script', '', ['src' => $url]) . "\n";
 
         } else {
             return '';
diff --git a/lib/outputrequirementslib.php b/lib/outputrequirementslib.php
index 3eb24e2b680..89bca869e3a 100644
--- a/lib/outputrequirementslib.php
+++ b/lib/outputrequirementslib.php
@@ -1467,14 +1467,14 @@ class page_requirements_manager {
         );
 
         if ($this->yui3loader->combine) {
-            return '<script type="text/javascript" src="' .
+            return '<script src="' .
                     $this->yui3loader->local_comboBase .
                     implode('&amp;', $baserollups) .
                     '"></script>';
         } else {
             $code = '';
             foreach ($baserollups as $rollup) {
-                $code .= '<script type="text/javascript" src="'.$this->yui3loader->local_comboBase.$rollup.'"></script>';
+                $code .= '<script src="'.$this->yui3loader->local_comboBase.$rollup.'"></script>';
             }
             return $code;
         }
diff --git a/lib/tablelib.php b/lib/tablelib.php
index 81a944a308e..067f9869f5c 100644
--- a/lib/tablelib.php
+++ b/lib/tablelib.php
@@ -1523,7 +1523,6 @@ class table_sql extends flexible_table {
     function __construct($uniqueid) {
         parent::__construct($uniqueid);
         // some sensible defaults
-        $this->set_attribute('cellspacing', '0');
         $this->set_attribute('class', 'generaltable generalbox');
     }
 
diff --git a/user/classes/participants_table.php b/user/classes/participants_table.php
index 0224f52c82c..5074d1d3eda 100644
--- a/user/classes/participants_table.php
+++ b/user/classes/participants_table.php
@@ -220,6 +220,9 @@ class participants_table extends \table_sql {
         $this->define_columns($columns);
         $this->define_headers($headers);
 
+        // The name column is a header.
+        $this->define_header_column('fullname');
+
         // Make this table sorted by last name by default.
         $this->sortable(true, 'lastname');
 
diff --git a/user/index.php b/user/index.php
index 6821dd4de77..b8b07c14923 100644
--- a/user/index.php
+++ b/user/index.php
@@ -278,7 +278,7 @@ if ($bulkoperations) {
     if ($participanttable->get_page_size() < $participanttable->totalrows) {
         // Select all users, refresh page showing all users and mark them all selected.
         $label = get_string('selectalluserswithcount', 'moodle', $participanttable->totalrows);
-        echo html_writer::tag('input', "", array('type' => 'button', 'id' => 'checkall', 'class' => 'btn btn-secondary',
+        echo html_writer::empty_tag('input', array('type' => 'button', 'id' => 'checkall', 'class' => 'btn btn-secondary',
                 'value' => $label, 'data-showallink' => $showalllink));
     }
     echo html_writer::end_tag('div');
@@ -338,14 +338,12 @@ if ($bulkoperations) {
         'data-toggle' => 'action',
         'disabled' => empty($selectall)
     );
-    echo html_writer::tag('div', html_writer::tag('label', get_string("withselectedusers"),
-        array('for' => 'formactionid', 'class' => 'col-form-label d-inline')) .
-        html_writer::select($displaylist, 'formaction', '', array('' => 'choosedots'), $selectactionparams));
+    $label = html_writer::tag('label', get_string("withselectedusers"),
+            ['for' => 'formactionid', 'class' => 'col-form-label d-inline']);
+    $select = html_writer::select($displaylist, 'formaction', '', ['' => 'choosedots'], $selectactionparams);
+    echo html_writer::tag('div', $label . $select);
 
-    echo '<input type="hidden" name="id" value="'.$course->id.'" />';
-    echo '<noscript style="display:inline">';
-    echo '<div><input type="submit" value="'.get_string('ok').'" /></div>';
-    echo '</noscript>';
+    echo '<input type="hidden" name="id" value="' . $course->id . '" />';
     echo '</div></div></div>';
     echo '</form>';
 
@@ -360,6 +358,8 @@ echo '</div>';  // Userlist.
 
 $enrolrenderer = $PAGE->get_renderer('core_enrol');
 echo '<div class="float-right">';
+// Need to re-generate the buttons to avoid having elements with duplicate ids on the page.
+$enrolbuttons = $manager->get_manual_enrol_buttons();
 foreach ($enrolbuttons as $enrolbutton) {
     echo $enrolrenderer->render($enrolbutton);
 }