diff -u b/core/modules/language/src/Config/LanguageConfigFactoryOverrideInterface.php b/core/modules/language/src/Config/LanguageConfigFactoryOverrideInterface.php
--- b/core/modules/language/src/Config/LanguageConfigFactoryOverrideInterface.php
+++ b/core/modules/language/src/Config/LanguageConfigFactoryOverrideInterface.php
@@ -16,7 +16,7 @@
    *
    * @return \Drupal\Core\Language\LanguageInterface|null
    *   The language object used to override configuration data or NULL, if not
-   *   set yet.
+   *   set yet, such as when Drupal is booted through a CLI.
    */
   public function getLanguage();
 
diff -u b/core/modules/language/src/ConfigurableLanguageManager.php b/core/modules/language/src/ConfigurableLanguageManager.php
--- b/core/modules/language/src/ConfigurableLanguageManager.php
+++ b/core/modules/language/src/ConfigurableLanguageManager.php
@@ -437,7 +437,7 @@
    * {@inheritdoc}
    */
   public function getConfigOverrideLanguage() {
-    // There might be cases where the language override was not set yet.
+    // If the current language is not overridden, pretend it is its override.
     return $this->configFactoryOverride->getLanguage() ?: $this->getCurrentLanguage();
   }