diff --git a/core/lib/Drupal/Core/Field/FieldDefinition.php b/core/lib/Drupal/Core/Field/FieldDefinition.php
index 708d2fe..c12c71f 100644
--- a/core/lib/Drupal/Core/Field/FieldDefinition.php
+++ b/core/lib/Drupal/Core/Field/FieldDefinition.php
@@ -336,7 +336,7 @@ public function getPropertyNames() {
    */
   public function getMainPropertyName() {
     $class = $this->getFieldItemClass();
-    return $class::getMainPropertyName();
+    return $class::mainPropertyName();
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/AllowedValuesConstraintValidator.php b/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/AllowedValuesConstraintValidator.php
index af0e38e..da5263a 100644
--- a/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/AllowedValuesConstraintValidator.php
+++ b/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/AllowedValuesConstraintValidator.php
@@ -30,7 +30,7 @@ public function validate($value, Constraint $constraint) {
 
       // If the data is complex, we have to validate its main property.
       if ($typed_data instanceof ComplexDataInterface) {
-        $name = $typed_data->getMainPropertyName();
+        $name = $typed_data->getDataDefinition()->getMainPropertyName();
         if (!isset($name)) {
           throw new \LogicException('Cannot validate allowed values for complex data without a main property.');
         }
diff --git a/core/modules/field/lib/Drupal/field/Entity/Field.php b/core/modules/field/lib/Drupal/field/Entity/Field.php
index 96ba183..332d794 100644
--- a/core/modules/field/lib/Drupal/field/Entity/Field.php
+++ b/core/modules/field/lib/Drupal/field/Entity/Field.php
@@ -837,7 +837,7 @@ public function getPropertyNames() {
    */
   public function getMainPropertyName() {
     $class = $this->getFieldItemClass();
-    return $class::getMainPropertyName();
+    return $class::mainPropertyName();
   }
 
   /**