diff --git a/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
index 81fa6af..7793151 100644
--- a/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -413,7 +413,7 @@ function template_preprocess_system_themes_page(&$variables) {
       // Make sure to provide feedback on compatibility.
       $current_theme['incompatible'] = '';
       if (!empty($theme->incompatible_core)) {
-        $current_theme['incompatible'] = t('This version is not compatible with Drupal !core_version and should be replaced.', array('!core_version' => \Drupal::CORE_COMPATIBILITY));
+        $current_theme['incompatible'] = t('This version is not compatible with Drupal !core_version and should be replaced. Check the .info.yml file contains the correct \'core\' value and that the theme includes a region called \'content\'.', array('!core_version' => \Drupal::CORE_COMPATIBILITY));
       }
       elseif (!empty($theme->incompatible_php)) {
         if (substr_count($theme->info['php'], '.') < 2) {