Drupal Release: 8.4.1

TL;DR

Drupal 8.4.1 is a maintenance release that addresses numerous bug fixes, documentation improvements, and code standards cleanup. Key fixes include resolving JavaScript errors when viewing non-latest entity revisions, fixing entity query issues with reference fields, addressing migration problems, and improving session handling. This release focuses on stability and quality improvements rather than introducing new features.

Highlight of the Release

• Fixed JavaScript errors when viewing non-latest entity revisions
• Resolved entity query issues with reference fields targeting the same entity type
• Fixed critical session handling issue in SessionCacheContext
• Improved migration from Drupal 6/7 with fixes for URLs, forum containers, and vocabularies
• Enhanced documentation for entity revisions and translations
• Improved test coverage and converted many web tests to browser tests

Migration Guide

No migration guide is necessary for this maintenance release as it doesn't introduce breaking changes. The fixes and improvements are backward compatible with Drupal 8.4.0.

For those who are migrating content from Drupal 6 or 7 to Drupal 8, this release includes several important fixes:

1. URLs without http:// are now properly handled during migration
2. Forum containers are now correctly migrated as containers rather than forums
3. Translated forum vocabularies no longer create duplicates
4. Vocabulary migration now correctly maps vid from machine_name instead of vocabulary name
5. Datetime fields are now migrated with the correct datetime_type

These improvements should make the migration process more reliable.

Upgrade Recommendations

This is a maintenance release that fixes several bugs and improves stability. It is recommended that all sites running Drupal 8.4.0 upgrade to this version.

The upgrade process should be straightforward:

1. Back up your database and code
2. Update your codebase to Drupal 8.4.1
3. Run the database updates via the update.php script or Drush

This release doesn't introduce breaking changes, so the upgrade should be smooth for most sites. However, as with any update, testing in a development environment before applying to production is always recommended.

Bug Fixes

Entity and Field Handling

• Fixed JavaScript errors thrown when viewing non-latest default revision of entity (Issue #2910005)
• Resolved entity query issues with two reference fields conditions targeting the same entity type (Issue #2759757)
• Fixed content entity form validation to respect the #limit_validation_errors property from field widgets (Issue #2901943)
• Corrected BlockContentModerationHandler::enforceRevisionsEntityFormAlter setting incorrect keys in form (Issue #2894765)
• Fixed fatal error with Call to a member function getTimestamp() (Issue #2573807)

Migration System

• Fixed forum containers being migrated as forums from Drupal 7 (Issue #2903007)
• Resolved issue with translated forum vocabulary migration creating duplicate forum vocabularies (Issue #2914249)
• Fixed vocabulary migration incorrectly mapping vid from vocabulary name instead of machine_name (Issue #2914649)
• Corrected datetime_type not being set correctly when migrating datetime fields from D7 (Issue #2894068)
• Fixed URLs without http:// being broken after migration from Drupal 6 or 7 (Issue #2897254)
• Fixed migrations with a highwater property not applying correct orderBy() on first run (Issue #2912120)
• Fixed issue where Migrate never unsets existing data for content entities (Issue #2711353)
• Fixed private and public file migrations using the same name (Issue #2916642)

Session and Cache

• Fixed SessionCacheContext calling getId() on null (Issue #2881348)
• Corrected description of cache invalidation tags (Issue #2913445)

UI and Display

• Fixed batch missing title on screen (Issue #2744663)
• Fixed Off-Canvas CSS reset preventing SVGs from displaying (Issue #2907420)
• Fixed REST views authentication (Issue #2825204)

Testing and Standards

• Fixed random fail in ContentEntityChangedTest::testChanged (Issue #2857843)
• Fixed various coding standards issues across multiple files
• Undid accidental commenting of messages in tests

New Features

This maintenance release focuses on bug fixes and improvements rather than introducing new features. The changes are primarily aimed at enhancing stability, fixing issues, improving documentation, and cleaning up code standards.

Security Updates

No specific security fixes were mentioned in the release notes. This appears to be primarily a maintenance release focused on bug fixes, documentation improvements, and code standards cleanup.

Performance Improvements

Performance Optimizations

• Improved array handling by using array_column instead of array_map where possible in the Workflows module (Issue #2902018)
• Made DateTimePlus calls chainable for better performance and code readability (Issue #2910081)
• Enhanced entity query performance with the ability to query the latest revision (Issue #2864995)

Impact Summary

Drupal 8.4.1 is a maintenance release that addresses numerous bugs and improves stability across the platform. The most significant impacts include:

1. Entity handling improvements: Fixed JavaScript errors when viewing non-latest entity revisions and resolved issues with entity queries involving reference fields.

2. Migration system enhancements: Multiple fixes for migrating content from Drupal 6/7, including proper handling of URLs, forum containers, vocabularies, and datetime fields.

3. Session handling fix: Resolved a critical issue in SessionCacheContext that could cause fatal errors.

4. Documentation improvements: Enhanced documentation for entity revisions and translations, API usage, and test coverage.

5. Code quality: Extensive cleanup of coding standards and improved test coverage with many web tests converted to browser tests.

This release primarily focuses on stability and quality improvements rather than introducing new features, making it a recommended update for all Drupal 8.4.0 sites.