diff --git a/include/class/document.class.php b/include/class/document.class.php
index 704ac7959..6019fff10 100644
--- a/include/class/document.class.php
+++ b/include/class/document.class.php
@@ -305,7 +305,7 @@ class Document
 
                         // if the pattern if found we replace it
                         $value=$this->replace($tag, $p_array);
-                        if (strpos($value, 'ERROR')!=false)
+                        if (strpos($value??"", 'ERROR')!=false)
                             $value="";
                         /*
                          * Change type of cell to numeric
diff --git a/include/lib/function_javascript.php b/include/lib/function_javascript.php
index 8c30a80c9..087863698 100644
--- a/include/lib/function_javascript.php
+++ b/include/lib/function_javascript.php
@@ -2719,7 +2719,7 @@ function unescapebycharacter($str)
  */
 function escape_xml($p_xml)
 {
-    $xml=$p_xml;
+    $xml=$p_xml??"";
     $xml=str_replace('&','&',$xml);
     $xml=str_replace('<','&lt;',$xml);
     $xml=str_replace('>','&gt;',$xml);
@@ -2737,7 +2737,7 @@ function escape_xml($p_xml)
  */
 function unescape_xml($p_xml)
 {
-    $xml=$p_xml;
+    $xml=$p_xml??"";
     $xml=str_replace('&amp;','&',$xml);
     $xml=str_replace('&lt;','<',$xml);
     $xml=str_replace('&gt;','>',$xml);