diff -u b/core/modules/system/src/Form/ModulesListForm.php b/core/modules/system/src/Form/ModulesListForm.php
--- b/core/modules/system/src/Form/ModulesListForm.php
+++ b/core/modules/system/src/Form/ModulesListForm.php
@@ -254,7 +254,7 @@
           '#href' => 'admin/help/' . $module->getName(),
           '#options' => array(
             'attributes' => array(
-            'id' => 'edit-modules-core-' . $module->name . '-links-help',
+            'id' => 'edit-modules-core-' . $module->getName() . '-links-help',
             'class' => array('module-link', 'module-link-help'),
             'title' => $this->t('Help'),
             ),
@@ -410,18 +410,18 @@
     }
 
     // Set id for checkbox here so module label can reference it.
-    $id = drupal_html_class('edit-modules-' . $module->info['package'] . '-' . $module->name . '-enable');
+    $id = drupal_html_class('edit-modules-' . $module->info['package'] . '-' . $module->getName() . '-enable');
 
     $row['name']['#markup'] = $module->info['name'];
 
     $row['enable'] += array(
       '#id' => $id,
-      '#parents' => array('modules', $module->info['package'], $module->name, 'enable'),
+      '#parents' => array('modules', $module->info['package'], $module->getName(), 'enable'),
     );
 
     // Add the module label and expand/collapse functionality.
     $row['name'] = array(
-      '#prefix' => '<label id="module-' . $module->name . '" for="' . $id . '" class="module-name table-filter-text-source">',
+      '#prefix' => '<label id="module-' . $module->getName() . '" for="' . $id . '" class="module-name table-filter-text-source">',
       '#markup' => $module->info['name'],
       '#suffix' => '</label>',
       '#wrapper_attributes' => array(
diff -u b/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
--- b/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -200,85 +200,6 @@
 }
 
 /**
- * Returns HTML for the modules form.
- *
- * @param $variables
- *   An associative array containing:
- *   - form: A render element representing the form.
- *
- * @ingroup themeable
- */
-function theme_system_modules_details($variables) {
-  $form = $variables['form'];
-
-  // Individual table headers.
-  $rows = array();
-  // Iterate through all the modules, which are children of this element.
-  foreach (Element::children($form) as $key) {
-    // Stick the key into $module for easier access.
-    $module = $form[$key];
-    // Create the row for the table.
-    $row = array();
-    // Add the checkbox into the first cell.
-    unset($module['enable']['#title']);
-    $module['#requires'] = array_filter($module['#requires']);
-    $module['#required_by'] = array_filter($module['#required_by']);
-
-    $requires = !empty($module['#requires']);
-    $required_by = !empty($module['#required_by']);
-    $version = !empty($module['version']['#markup']);
-
-    $row[] = array('class' => array('checkbox'), 'data' => drupal_render($module['enable']));
-
-    // Add the module label and expand/collapse functionalty.
-    $col2 = '<label id="module-' . $key . '" for="' . $module['enable']['#id'] . '" class="module-name table-filter-text-source">' . drupal_render($module['name']) . '</label>';
-    $row[] = array('class' => array('module'), 'data' => SafeMarkup::set($col2));
-
-    // Add the description, along with any modules it requires.
-    $description = '';
-    if ($version || $requires || $required_by) {
-      $description .= ' <div class="requirements">';
-      if ($version) {
-        $description .= '<div class="admin-requirements">' . t('Version: !module-version', array('!module-version' => drupal_render($module['version']))) . '</div>';
-      }
-      if ($requires) {
-        $description .= '<div class="admin-requirements">' . t('Requires: !module-list', array('!module-list' => implode(', ', $module['#requires']))) . '</div>';
-      }
-      if ($required_by) {
-        $description .= '<div class="admin-requirements">' . t('Required by: !module-list', array('!module-list' => implode(', ', $module['#required_by']))) . '</div>';
-      }
-      $description .= '</div>';
-    }
-    $links = '';
-    foreach (array('help', 'permissions', 'configure') as $key) {
-      $links .= drupal_render($module['links'][$key]);
-    }
-    if ($links) {
-      $description .= '  <div class="links">';
-      $description .= $links;
-      $description .= '</div>';
-    }
-    $details = array(
-      '#type' => 'details',
-      '#title' => SafeMarkup::set('<span class="text"> ' . drupal_render($module['description']) . '</span>'),
-      '#attributes' => array('id' => $module['enable']['#id'] . '-description'),
-      '#description' => SafeMarkup::set($description),
-    );
-    $col4 = drupal_render($details);
-    $row[] = array('class' => array('description', 'expand'), 'data' => $col4);
-
-    $rows[] = $module['#attributes'] + array('data' => $row);
-  }
-
-  $table = array(
-    '#type' => 'table',
-    '#header' => $form['#header'],
-    '#rows' => $rows,
-  );
-  return drupal_render($table);
-}
-
-/**
  * Prepares variables for appearance page templates.
  *
  * Default template: system-themes-page.html.twig.