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Dealing with errors in Drupal development is a common occurrence, and understanding how to interpret and resolve them is essential for smooth development workflows. In this article, we'll delve into a specific error message related to render arrays in Drupal and discuss steps to diagnose and fix the issue.


The error

User error: "attributes" is an invalid render array key in Drupal\Core\Render\Element::children() (line 98 of core/lib/Drupal/Core/Render/Element.php).

Drupal\Core\Render\Element::children(Array, 1) (Line: 416)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 204)
Drupal\Core\Render\Renderer->render(Array) (Line: 474)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 135)
__TwigTemplate_f69b0ceba0d56d31d1798b54707449ff->macro_renderTitle(Array) (Line: 1226)
twig_call_macro(Object, 'macro_renderTitle', Array, 65, Array, Object) (Line: 95)
__TwigTemplate_f69b0ceba0d56d31d1798b54707449ff->doDisplay(Array, Array) (Line: 394)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 367)
Twig\Template->display(Array) (Line: 379)
Twig\Template->render(Array, Array) (Line: 40)
Twig\TemplateWrapper->render(Array) (Line: 53)
twig_render_template('themes/custom/orw/templates/field/field--expert--paragraph--related-articles.html.twig', Array) (Line: 372)
Drupal\Core\Theme\ThemeManager->render('field', Array) (Line: 445)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 458)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 204)
Drupal\Core\Render\Renderer->render(Array) (Line: 474)


Detailing the error message

The error message provided indicates an issue with the "attributes" key within a render array. Let's break down the error message to understand its components:

User error – indicates that the error is within the user's control, likely originating from custom code or configurations.
Description – "'attributes' is an invalid render array key" specifies the nature of the error, suggesting that the "attributes" key is being used incorrectly.
Location – the error occurs in "Drupal\Core\Render\Element::children()" on line 98 of Element.php, providing a starting point for debugging.


Unpacking the situation

To understand the error further, we need to analyse the code snippet where the error originates. The snippet is part of a foreach loop iterating over elements, checking for the validity of render array keys. However, the error message doesn't provide detailed information about the specific element causing the issue.

foreach ($elements as $key => $value) {
      if (is_int($key) || $key === '' || $key[0] !== '#') {
        if (is_array($value)) {
          if (isset($value['#weight'])) {
            $weight = $value['#weight'];
            $sortable = TRUE;
          else {
            $weight = 0;
          // Supports weight with up to three digit precision and conserve
          // the insertion order.
          $child_weights[$key] = floor($weight * 1000) + $i / $count;
        // Only trigger an error if the value is not null.
        // @see
        elseif (isset($value)) {
          trigger_error(new FormattableMarkup('"@key" is an invalid render array key', ['@key' => $key]), E_USER_ERROR);


Enhancing Error Details

To gather more information for debugging, we can modify the error handling code to include additional details. By adding a print_r statement, we can capture the specific element that triggered the error, making debugging more effective.

trigger_error(new FormattableMarkup('"@key" is an invalid render array key in the value @value from the elements @elements', ['@key' => $key, '@value' => print_r($value, true), '@elements' => print_r($elements, true)]), E_USER_ERROR);

This modification provides insights into the problematic element and the overall elements array, aiding in pinpointing the root cause of the error.


The wrap

Understanding and resolving Drupal errors requires a systematic approach, including careful analysis of error messages and code snippets. By enhancing error details and leveraging debugging techniques like print_r, developers can efficiently diagnose and fix issues, ensuring smoother Drupal development processes.


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