diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index 7532952f55c..b0f51149c83 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -7801,7 +7801,14 @@ function get_plugin_list_with_function($plugintype, $function, $file = 'lib.php'
             $filepath = $allplugins[$pluginname] . DIRECTORY_SEPARATOR . $file;
             if (file_exists($filepath)) {
                 include_once($filepath);
-                $pluginfunctions[$plugintype . '_' . $pluginname] = $functionname;
+
+                // Now that the file is loaded, we must verify the function still exists.
+                if (function_exists($functionname)) {
+                    $pluginfunctions[$plugintype . '_' . $pluginname] = $functionname;
+                } else {
+                    // Invalidate the cache for next run.
+                    \cache_helper::invalidate_by_definition('core', 'plugin_functions');
+                }
             }
         }
     }
@@ -7834,6 +7841,7 @@ function get_plugins_with_function($function, $file = 'lib.php', $include = true
     // Clearning the filename as cache_helper::hash_key only allows a-zA-Z0-9_.
     $key = $function . '_' . clean_param($file, PARAM_ALPHA);
     $pluginfunctions = $cache->get($key);
+    $dirty = false;
 
     // Use the plugin manager to check that plugins are currently installed.
     $pluginmanager = \core_plugin_manager::instance();
@@ -7848,14 +7856,14 @@ function get_plugins_with_function($function, $file = 'lib.php', $include = true
             foreach ($plugins as $plugin => $function) {
                 if (!isset($installedplugins[$plugin])) {
                     // Plugin code is still present on disk but it is not installed.
-                    unset($pluginfunctions[$plugintype][$plugin]);
-                    continue;
+                    $dirty = true;
+                    break 2;
                 }
 
                 // Cache might be out of sync with the codebase, skip the plugin if it is not available.
                 if (empty($allplugins[$plugin])) {
-                    unset($pluginfunctions[$plugintype][$plugin]);
-                    continue;
+                    $dirty = true;
+                    break 2;
                 }
 
                 $fileexists = file_exists($allplugins[$plugin] . DIRECTORY_SEPARATOR . $file);
@@ -7864,11 +7872,22 @@ function get_plugins_with_function($function, $file = 'lib.php', $include = true
                     include_once($allplugins[$plugin] . DIRECTORY_SEPARATOR . $file);
                 } else if (!$fileexists) {
                     // If the file is not available any more it should not be returned.
-                    unset($pluginfunctions[$plugintype][$plugin]);
+                    $dirty = true;
+                    break 2;
+                }
+
+                // Check if the function still exists in the file.
+                if ($include && !function_exists($function)) {
+                    $dirty = true;
+                    break 2;
                 }
             }
         }
-        return $pluginfunctions;
+
+        // If the cache is dirty, we should fall through and let it rebuild.
+        if (!$dirty) {
+            return $pluginfunctions;
+        }
     }
 
     $pluginfunctions = array();