diff --git a/lib/pear/HTML/Common.php b/lib/pear/HTML/Common.php
index b86217910a5..3797cc3b736 100644
--- a/lib/pear/HTML/Common.php
+++ b/lib/pear/HTML/Common.php
@@ -168,7 +168,7 @@ class HTML_Common {
 
         if (is_array($attributes)) {
             foreach ($attributes as $key => $value) {
-                $strAttr .= ' ' . $key . '="' . htmlspecialchars($value) . '"';
+                $strAttr .= ' ' . $key . '="' . htmlspecialchars($value ?? '') . '"';
             }
         }
         return $strAttr;
diff --git a/lib/pear/HTML/QuickForm.php b/lib/pear/HTML/QuickForm.php
index c1a8473efac..fe0fcac580b 100644
--- a/lib/pear/HTML/QuickForm.php
+++ b/lib/pear/HTML/QuickForm.php
@@ -733,7 +733,7 @@ class HTML_QuickForm extends HTML_Common {
     {
         static $anonGroups = 1;
 
-        if (0 == strlen($name)) {
+        if (0 == strlen($name ?? '')) {
             $name       = 'qf_group_' . $anonGroups++;
             $appendName = false;
         }
@@ -813,6 +813,7 @@ class HTML_QuickForm extends HTML_Common {
     function getSubmitValue($elementName)
     {
         $value = null;
+        $elementName = $elementName ?? '';
         if (isset($this->_submitValues[$elementName]) || isset($this->_submitFiles[$elementName])) {
             $value = isset($this->_submitValues[$elementName])? $this->_submitValues[$elementName]: array();
             if (is_array($value) && isset($this->_submitFiles[$elementName])) {
diff --git a/lib/pear/HTML/QuickForm/RuleRegistry.php b/lib/pear/HTML/QuickForm/RuleRegistry.php
index 08ba246891a..baa506d8b1f 100644
--- a/lib/pear/HTML/QuickForm/RuleRegistry.php
+++ b/lib/pear/HTML/QuickForm/RuleRegistry.php
@@ -76,7 +76,7 @@ class HTML_QuickForm_RuleRegistry
      */
     function registerRule($ruleName, $type, $data1, $data2 = null)
     {
-        $type = strtolower($type);
+        $type = strtolower($type ?? '');
         if ($type == 'regex') {
             // Regular expression
             $rule =& $this->getRule('regex');
diff --git a/lib/pear/HTML/QuickForm/element.php b/lib/pear/HTML/QuickForm/element.php
index 042f1910d63..37e2e1bbff7 100644
--- a/lib/pear/HTML/QuickForm/element.php
+++ b/lib/pear/HTML/QuickForm/element.php
@@ -351,7 +351,7 @@ class HTML_QuickForm_element extends HTML_Common
         if (empty($values)) {
             return null;
         }
-        $elementName = $this->getName();
+        $elementName = $this->getName() ?? '';
         if (isset($values[$elementName])) {
             return $values[$elementName];
         } elseif (strpos($elementName, '[')) {
@@ -447,7 +447,7 @@ class HTML_QuickForm_element extends HTML_Common
             return;
         }
 
-        $id = $this->getName();
+        $id = $this->getName() ?? '';
         $id = 'id_' . str_replace(array('qf_', '[', ']'), array('', '_', ''), $id);
         $id = clean_param($id, PARAM_ALPHANUMEXT);
         $this->updateAttributes(array('id' => $id));
diff --git a/lib/pear/readme_moodle.txt b/lib/pear/readme_moodle.txt
index 3a8a9efe6a5..bf506807bf5 100644
--- a/lib/pear/readme_moodle.txt
+++ b/lib/pear/readme_moodle.txt
@@ -32,6 +32,7 @@ MDL-70457 - PHP 7.4 curly brackets string access fix.
 MDL-71126 - Quiz: Manual grading page size preference can get stuck at 0
             Including in this change:
              - New positiveint regex rule to check if the value is a positive integer
+MDL-76102 - PHP 8.1 passing null to a non-nullable argument of a built-in function is deprecated
 
 Pear
 ====