diff -u b/core/lib/Drupal/Core/Extension/module.api.php b/core/lib/Drupal/Core/Extension/module.api.php
--- b/core/lib/Drupal/Core/Extension/module.api.php
+++ b/core/lib/Drupal/Core/Extension/module.api.php
@@ -784,7 +784,7 @@
   return [
     'mymodule_post_update_foo' => '8.x-3.0',
     'mymodule_post_update_bar' => '8.x-3.0',
-    'mymodule_post_update_baz' => '8.x-3.0',
+    'mymodule_post_update_baz' => '8.x-4.0',
   ];
 }
 
diff -u b/core/lib/Drupal/Core/Update/RemovedPostUpdateNameException.php b/core/lib/Drupal/Core/Update/RemovedPostUpdateNameException.php
--- b/core/lib/Drupal/Core/Update/RemovedPostUpdateNameException.php
+++ b/core/lib/Drupal/Core/Update/RemovedPostUpdateNameException.php
@@ -5,8 +5,8 @@
 /**
  * An exception thrown for removed post-update functions.
  *
- * Occurs when a module defines hook_post_update_NAME() that are also
- * specified has having been removed in hook_removed_post_updates().
+ * Occurs when a module defines hook_post_update_NAME() implementations that are
+ * listed as removed in hook_removed_post_updates().
  */
 class RemovedPostUpdateNameException extends \LogicException {
 }
diff -u b/core/modules/system/system.install b/core/modules/system/system.install
--- b/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -1149,7 +1149,7 @@
         if ($missing_updates = array_diff(array_keys($removed_post_updates), $existing_updates)) {
           $versions = array_unique(array_intersect_key($removed_post_updates, array_flip($missing_updates)));
           $description = new PluralTranslatableMarkup(count($versions),
-            'The installed version of the %module module is too old to update. Update to a version prior to @versions first (missing update: @missing_updates).',
+            'The installed version of the %module module is too old to update. Update to a version prior to @versions first (missing updates: @missing_updates).',
             'The installed version of the %module module is too old to update. Update first to a version prior to all of the following: @versions (missing updates: @missing_updates).',
             [
               '%module' => $module_info->info['name'],
diff -u b/core/modules/system/tests/modules/update_test_postupdate/update_test_postupdate.post_update.php b/core/modules/system/tests/modules/update_test_postupdate/update_test_postupdate.post_update.php
--- b/core/modules/system/tests/modules/update_test_postupdate/update_test_postupdate.post_update.php
+++ b/core/modules/system/tests/modules/update_test_postupdate/update_test_postupdate.post_update.php
@@ -75,6 +75,7 @@
   return [
     'update_test_postupdate_post_update_foo' => '8.x-1.0',
-    'update_test_postupdate_post_update_bar' => '8.x-2.0',
-    'update_test_postupdate_post_update_baz' => '3.0.0',
+    'update_test_postupdate_post_update_bar' => '8.x-1.0',
+    'update_test_postupdate_post_update_baz' => '8.x-2.0',
+    'update_test_postupdate_post_update_qux' => '3.0.0',
   ];
 }
diff -u b/core/modules/system/tests/src/Functional/Module/InstallUninstallTest.php b/core/modules/system/tests/src/Functional/Module/InstallUninstallTest.php
--- b/core/modules/system/tests/src/Functional/Module/InstallUninstallTest.php
+++ b/core/modules/system/tests/src/Functional/Module/InstallUninstallTest.php
@@ -308,6 +308,7 @@
           'update_test_postupdate_post_update_foo',
           'update_test_postupdate_post_update_bar',
           'update_test_postupdate_post_update_baz',
+          'update_test_postupdate_post_update_qux',
         ];
         $this->assertSame($expected, $existing_updates);
         break;