diff --git a/core/modules/views/src/Plugin/views/filter/FilterPluginBase.php b/core/modules/views/src/Plugin/views/filter/FilterPluginBase.php
index 335fd99..c53d905 100644
--- a/core/modules/views/src/Plugin/views/filter/FilterPluginBase.php
+++ b/core/modules/views/src/Plugin/views/filter/FilterPluginBase.php
@@ -1382,7 +1382,11 @@ public function acceptExposedInput($input) {
     }
 
     if (!empty($this->options['expose']['identifier'])) {
-      $value = $input[$this->options['expose']['identifier']];
+      if (isset($input[$this->options['expose']['identifier']])) {
+        $value = $input[$this->options['expose']['identifier']];
+      } else {
+        return FALSE;
+      }
 
       // Various ways to check for the absence of non-required input.
       if (empty($this->options['expose']['required'])) {