Index: libraries/DisplayResults.php
===================================================================
--- phpMyAdmin-4.7.8-all-languages/libraries/DisplayResults.php
+++ phpMyAdmin-4.7.8-all-languages/libraries/DisplayResults.php	2018-12-15 21:37:09.814066411 +0100
@@ -3061,9 +3061,9 @@
 
                     if (@file_exists($include_file)) {
 
-                        include_once $include_file;
                         $class_name = PMA_getTransformationClassName($include_file);
                         // todo add $plugin_manager
+                        if (class_exists($class_name)) {
                         $plugin_manager = null;
                         $transformation_plugin = new $class_name(
                             $plugin_manager
@@ -3083,7 +3083,7 @@
                             '_', '/',
                             $mime_map[$orgFullColName]['mimetype']
                         );
-
+                        }
                     } // end if file_exists
                 } // end if transformation is set
             } // end if mime/transformation works.