diff --git a/lib/classes/string_manager_standard.php b/lib/classes/string_manager_standard.php
index 1a3f36400c8..140ba650925 100644
--- a/lib/classes/string_manager_standard.php
+++ b/lib/classes/string_manager_standard.php
@@ -533,7 +533,13 @@ class core_string_manager_standard implements core_string_manager {
                     $languages[$langcode] = !empty($this->transaliases[$langcode]) ? $this->transaliases[$langcode] : $langname;
                 }
             }
-            return $languages;
+
+            // If there are no valid enabled translations, then return all languages.
+            if (!empty($languages)) {
+                return $languages;
+            } else {
+                return $cachedlist;
+            }
         }
 
         // Get all languages available in system.
@@ -584,7 +590,12 @@ class core_string_manager_standard implements core_string_manager {
             }
         }
 
-        return $languages;
+        // If there are no valid enabled translations, then return all languages.
+        if (!empty($languages)) {
+            return $languages;
+        } else {
+            return $cachedlist;
+        }
     }
 
     /**
diff --git a/lib/tests/string_manager_standard_test.php b/lib/tests/string_manager_standard_test.php
index aa73a0e6a9d..c167707e874 100644
--- a/lib/tests/string_manager_standard_test.php
+++ b/lib/tests/string_manager_standard_test.php
@@ -140,6 +140,13 @@ class core_string_manager_standard_testcase extends advanced_testcase {
 
         $this->assertEquals(['en' => 'En'], $stringman->get_list_of_translations());
 
+        // Set invalid config, ensure original list is returned.
+        set_config('langlist', 'xx');
+        $this->assertEquals(['en' => 'English ‎(en)‎'], get_string_manager(true)->get_list_of_translations());
+
+        set_config('langlist', 'xx,en|En');
+        $this->assertEquals(['en' => 'En'], get_string_manager(true)->get_list_of_translations());
+
         set_config('langlist', '');
         get_string_manager(true);
     }