diff --git a/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
index 898a8a5568..ca5a51326f 100644
--- a/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
+++ b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
@@ -160,6 +255,9 @@ public function submitForm(array &$form, FormStateInterface $form_state) {
   public function buildOverviewForm(array $form, FormStateInterface $form_state) {
     $form['#title'] = $this->t('Upgrade');
 
+    // Add the no upgrade path array to the form state so it can be altered.
+    $form_state->set('no_upgrade_paths', $this->noUpgradePaths);
+
     if ($date_performed = $this->state->get('migrate_drupal_ui.performed')) {
       // @todo Add back support for rollbacks and incremental migrations.
       //   https://www.drupal.org/node/2687843
diff --git a/core/modules/migrate_drupal_ui/tests/modules/upgrade_form_alter_test/upgrade_form_alter_test.info.yml b/core/modules/migrate_drupal_ui/tests/modules/upgrade_form_alter_test/upgrade_form_alter_test.info.yml
new file mode 100644
index 0000000000..c6b66cdb34
--- /dev/null
+++ b/core/modules/migrate_drupal_ui/tests/modules/upgrade_form_alter_test/upgrade_form_alter_test.info.yml
@@ -0,0 +1,6 @@
+name: 'Upgrade form alter test'
+type: module
+description: 'Tests that contrib modules can alter the upgrade form.'
+package: Testing
+version: VERSION
+core: 8.x
diff --git a/core/modules/migrate_drupal_ui/tests/modules/upgrade_form_alter_test/upgrade_form_alter_test.module b/core/modules/migrate_drupal_ui/tests/modules/upgrade_form_alter_test/upgrade_form_alter_test.module
new file mode 100644
index 0000000000..8855721dc3
--- /dev/null
+++ b/core/modules/migrate_drupal_ui/tests/modules/upgrade_form_alter_test/upgrade_form_alter_test.module
@@ -0,0 +1,18 @@
+<?php
+
+/**
+ * @file
+ * Test module for altering the upgrade form.
+ */
+
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Implements hook_form_FORM_ID_alter().
+ */
+function upgrade_form_alter_test_form_migrate_drupal_ui_form_alter(array &$form, FormStateInterface $form_state, $form_id) {
+  $no_upgrade_paths = $form_state->get('no_upgrade_paths');
+  $no_upgrade_paths['6'][] = 'event';
+  $no_upgrade_paths['7'][] = 'book';
+  $form_state->set('no_upgrade_paths', $no_upgrade_paths);
+}
diff --git a/core/modules/migrate_drupal_ui/tests/src/Functional/d7/MigrateUpgrade7Test.php b/core/modules/migrate_drupal_ui/tests/src/Functional/d7/MigrateUpgrade7Test.php
index 1e93d8d840..4955acbd24 100644
--- a/core/modules/migrate_drupal_ui/tests/src/Functional/d7/MigrateUpgrade7Test.php
+++ b/core/modules/migrate_drupal_ui/tests/src/Functional/d7/MigrateUpgrade7Test.php
@@ -30,6 +30,7 @@ class MigrateUpgrade7Test extends MigrateUpgradeTestBase {
     'forum',
     'statistics',
     'migration_provider_test',
+    'upgrade_form_alter_test',
   ];
 
   /**
@@ -133,9 +132,25 @@ protected function getAvailablePaths() {
       'system',
       'taxonomy',
       'text',
-      'translation',
       'user',
-      'user_reference',
+      // Include modules that do not have an upgrade path and are enabled in the
+      // source database, defined in the $noUpgradePath property
+      // in MigrateUpgradeForm.
+      'blog',
+      'contextual',
+      'date_api',
+      'entity',
+      'field_ui',
+      'help',
+      'php',
+      'simpletest',
+      'toolbar',
+      'translation',
+      'trigger',
+      // To test that contrib modules can alter this list, Book is added here
+      // by a hook_form_alter().
+      // @see upgrade_form_alter_test_form_migrate_drupal_ui_form_alter().
+      'book',
     ];
   }
 
@@ -144,21 +159,15 @@ protected function getAvailablePaths() {
    */
   protected function getMissingPaths() {
     return [
-      'blog',
-      'book',
+      // To test that contrib modules can alter this list, Book is removed from
+      // here by a hook_form_alter().
+      // @see upgrade_form_alter_test_form_migrate_drupal_ui_form_alter().
       'color',
-      'contextual',
-      'date_api',
-      'entity',
-      'field_ui',
-      'help',
-      'php',
       'rdf',
-      'simpletest',
+      // These modules are in the missing path list because they are installed
+      // on the source site but they are not installed on the destination site.
       'syslog',
-      'toolbar',
       'tracker',
-      'trigger',
       'update',
     ];
   }