diff --git a/core/modules/system/src/Tests/Render/Element/SelectTest.php b/core/modules/system/src/Tests/Render/Element/SelectTest.php
index 88e781e..f5e5021 100644
--- a/core/modules/system/src/Tests/Render/Element/SelectTest.php
+++ b/core/modules/system/src/Tests/Render/Element/SelectTest.php
@@ -60,6 +60,7 @@ public function testRendering() {
       // to supply some default values.
       $element += [
         '#id' => 'edit-select',
+        '#name' => 'test_select',
         '#parents' => [],
         '#array_parents' => [],
         '#tree' => FALSE,
@@ -70,7 +71,7 @@ public function testRendering() {
       $output = $test_case['output'];
       // The wrapper element never changes, so avoid having to specify it every
       // time.
-      $output = '<div class="form-item form-type-select">' . $output . '</div>';
+      $output = '<div class="form-item form-type-select form-item-test-select">' . $output . '</div>';
 
       $form_id = 'select';
       $form_state = new FormState();
@@ -102,7 +103,7 @@ public function providerTestSelect() {
     ];
     $test_case['output'] = <<<HTML
 <label for="edit-select">Test select</label>
-<select id="edit-select" class="form-select">
+<select id="edit-select" name="test_select" class="form-select">
 </select>
 HTML;
     $test_cases[] = $test_case;
@@ -121,7 +122,7 @@ public function providerTestSelect() {
     ];
     $test_case['output'] = <<<HTML
 <label for="edit-select">Test select</label>
-<select id="edit-select" class="form-select">
+<select id="edit-select" name="test_select" class="form-select">
   <option value="spring">Spring</option>
   <option value="summer">Summer</option>
   <option value="fall">Fall</option>
@@ -155,7 +156,7 @@ public function providerTestSelect() {
     ];
     $test_case['output'] = <<<HTML
 <label for="edit-select" class="form-required">Test select</label>
-<select id="edit-select" class="form-select required" required="required" aria-required="true">
+<select id="edit-select" name="test_select" class="form-select required" required="required" aria-required="true">
   <option value="" selected="selected">- Select -</option>
   <option value="spring">Spring</option>
   <option value="summer">Summer</option>
@@ -197,7 +198,7 @@ public function providerTestSelect() {
     ];
     $test_case['output'] = <<<HTML
 <label for="edit-select">Test select</label>
-<select id="edit-select" class="form-select">
+<select id="edit-select" name="test_select" class="form-select">
   <optgroup label="Seasons">
     <option value="spring">Spring</option>
     <option value="summer">Summer</option>
@@ -255,7 +256,7 @@ public function providerTestSelect() {
     ];
     $test_case['output'] = <<<HTML
 <label for="edit-select">Test select</label>
-<select id="edit-select" class="form-select">
+<select id="edit-select" name="test_select" class="form-select">
   <option data-league="nfl" value="football">Football</option>
   <option data-league="mlb" value="baseball">Baseball</option>
   <option data-league="nba" value="basketball">Basketball</option>
@@ -294,7 +295,7 @@ public function providerTestSelect() {
     ];
     $test_case['output'] = <<<HTML
 <label for="edit-select">Test select</label>
-<select id="edit-select" class="form-select">
+<select id="edit-select" name="test_select" class="form-select">
   <optgroup data-option-count="4" label="Seasons">
     <option value="spring">Spring</option>
     <option value="summer">Summer</option>
@@ -331,7 +332,7 @@ public function providerTestSelect() {
     ];
     $test_case['output'] = <<<HTML
 <label for="edit-select">Test select</label>
-<select id="edit-select" class="form-select">
+<select id="edit-select" name="test_select" class="form-select">
   <option value="football">Football</option>
   <option value="baseball">Baseball</option>
   <optgroup label="Seasons">
diff --git a/core/modules/views/src/Plugin/views/filter/InOperator.php b/core/modules/views/src/Plugin/views/filter/InOperator.php
index 268e172..13e4ae6 100644
--- a/core/modules/views/src/Plugin/views/filter/InOperator.php
+++ b/core/modules/views/src/Plugin/views/filter/InOperator.php
@@ -436,7 +436,7 @@ public function validate() {
       }
 
       // Some filter_in_operator usage uses optgroups forms, so flatten it.
-      $flat_options = OptGroup::flattenOptions($this->value_options);
+      $flat_options = OptGroup::flattenOptions($this->valueOptions);
 
       // Remove every element which is not known.
       foreach ($this->value as $value) {
