1. 1. make a full backup of your site (files and database)
  2. 2. using FTP or your web host control panel file manager, navigate to the "application/blocks" folder
  3. 3. create a new folder called "html"
  4. application/blocks/html
  5. 4. inside the new "html" folder, create a file called "view.php"
  6. application/blocks/html/view.php
  7. 5. open "view.php" and add the following code:
  9. <?php defined('C5_EXECUTE') or die('Access Denied.'); ?>
  10. <pre style="border: 8px solid red; min-height: 100px; min-width: 100px;">
  11.     <code>
  12.         <?php echo htmlentities($content); ?>
  13.     </code>
  14. </pre>
  17. I believe this should prevent the HTML blocks from executing code and will make them visible. The HTML content will be displayed as text with a pink background and a red border. This should allow you to identify the problem HTML blocks.
  19. After you have identified the problem HTML blocks, you can remove the created "view.php" to restore the default HTML block display.