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Troubleshooting

Common issues and solutions for Canvas Override.

Canvas Tab Not Visible

Symptoms

The Canvas tab does not appear on content pages.

Possible Causes and Solutions

1. Canvas Override not enabled on the content type

Go to Structure > Content types, edit the content type, and check that the Canvas layout checkbox is enabled in the vertical tabs.

2. User lacks permissions

The user needs at least one of: - Administer Canvas Override - Use Canvas Override for all content types - Use Canvas Override for [specific content type]

Check permissions at People > Permissions (/admin/people/permissions).

Verify via Drush: 

drush role:perm:list editor | grep canvas

3. Cache needs clearing

drush cr

4. Canvas module not installed

Canvas Override requires the Canvas module. Verify it is installed:

drush pm:list --filter=canvas

Required Field Validation Errors

Symptoms

Saving content in the Canvas editor produces validation errors for required fields (e.g. "Body field is required").

Explanation

Canvas Override edits only the layout and title. Other required fields are not present in the Canvas editor form. The module includes multiple safeguards to prevent validation failures:

  • Removes NotNull constraints from non-layout fields during Canvas API requests.
  • Restores required field values from the database before validation.
  • Restores field values before content save.

Solutions

  1. Update to the latest version of both Canvas and Canvas Override.

  2. Clear caches: 

    drush cr

  3. Check for conflicting modules that alter content validation or form processing.

  4. Verify field values exist: If a required field was recently added but has no stored value, the restoration logic cannot retrieve an original value. Ensure existing content has values for all required fields before editing in Canvas.

Page Data Panel Shows Entity Fields

Symptoms

The Canvas editor's Page data panel displays entity fields (body, images, etc.) instead of being hidden.

Explanation

Canvas Override hides entity fields from the Page data panel because field content is managed through the standard Drupal edit form, not the Canvas editor.

Solutions

  1. Clear caches: 

    drush cr

  2. Verify the module is enabled: 

    drush pm:list --filter=canvas_override

  3. Check module execution order: Another module may be altering the form display after Canvas Override. Check for conflicting hook implementations.

Layout Not Rendering on Content View

Symptoms

Content with a per-content Canvas layout does not display the custom layout on the full content view.

Possible Causes

1. Wrong view mode

Canvas Override only affects the full view mode. If viewing in teaser or another view mode, the per-content layout is not used.

2. View display misconfigured

Check that field_canvas_layout is enabled on the full view display with the canvas_naive_render_sdc_tree formatter:

  1. Go to Structure > Content types > [Type] > Manage display.
  2. Select the Full content view mode.
  3. Verify field_canvas_layout is visible and using the correct formatter.

3. Empty field

The field_canvas_layout field may be empty. Open the Canvas editor on the content item and save a layout.

Reset Not Working

Symptoms

Clicking "Reset to default layout" does not revert the content to the ContentTemplate default.

Solutions

  1. Verify the route: Visit /node/{id}/canvas/reset directly.

  2. Check permissions: The user needs Canvas Override permissions to access the reset route.

  3. Clear caches after resetting: 

    drush cr

Field Not Created on Content Type

Symptoms

Enabling Canvas Override on a content type does not create the field_canvas_layout field.

Solutions

  1. Check for errors in the Drupal log at Reports > Recent log messages (/admin/reports/dblog).

  2. Verify Canvas module: The component_tree field type is provided by Canvas. Ensure Canvas is installed and working: 

    drush pm:list --filter=canvas

  3. Create manually if automatic creation fails: 

    drush php:eval "\Drupal\canvas_override\Hook\CanvasOverrideHooks::ensureCanvasField('article');"

Performance Issues

Symptoms

Pages with per-content Canvas layouts load slowly.

Solutions

  1. Check the component tree size: Very large component trees with many nested components may affect rendering time. Simplify the layout if possible.

  2. Enable caching: Ensure Drupal's render cache and page cache are enabled: 

    drush state:set system.performance 'cache.page.max_age' 3600

  3. Review custom components: Slow components affect all pages that use them, not just Canvas Override pages.

Quick Diagnostic Commands

Use these commands to quickly diagnose Canvas Override issues:

# Check module status
drush pm:list --filter=canvas

# Check if Canvas Override is enabled on a content type
drush php:eval "echo \Drupal\node\Entity\NodeType::load('article')->getThirdPartySetting('canvas_override', 'enabled', FALSE) ? 'enabled' : 'disabled';"

# Check permissions for a role
drush role:perm:list editor | grep canvas

# Clear all caches
drush cr

# Check for errors in the log
drush watchdog:show --severity=error --count=10

Getting Help