Following error occurred after updating composer.json through Github Action 

  • Warning: Undefined array key "#markup" in Drupal\Core\Render\Renderer->doRender() (line 327 of core/lib/Drupal/Core/Render/Renderer.php).

Comments

lxpcfly’s picture

You need to trace the source of warning 

\Drupal::logger('module_name')->notice('<pre>' . print_r($render_array, TRUE) . '</pre>');