1. Create a new page.
  2. Add a Formatted Text & Images part to it.
  3. When editing the Formatted Text & Images part, select the Insert tab.
  4. Click the Merge Fields button.
  5. Select the "Error Fields" selection and double click on:
    'Error code'
    'Error description'
    and 'Error log ID'
    Also feel free to insert any image or extra text you desire, for example:
  6. Click Save
  7. Go to Administration, Sites & Settings, Click on your Site
  8. Scroll down to the Pages section
  9. For the "Error Page" drop-down, select the new error page you created
  10. Scroll to the top and click Save.