Drupal Release: 8.1.6

TL;DR

Drupal 8.1.6 is a maintenance release that addresses several issues including documentation updates, bug fixes, and performance improvements. It removes the Twig C extension requirement, fixes a critical update path issue, and corrects documentation for CKEditor stylesheets. This release is important for sites running Drupal 8.1.x to ensure stability and proper functionality.

Highlight of the Release

• Fixed critical update path issue that could break sites when updating from 8.1.3 to 8.1.4
• Removed Twig C extension requirement for better compatibility with modern PHP versions
• Updated documentation for adding CKEditor stylesheets
• Fixed array modification issue in ConfigDependencyManager

Migration Guide

No specific migration steps are required for this maintenance release. Standard update procedures apply:

1. Back up your database and site files
2. Put the site into maintenance mode
3. Update Drupal core files
4. Run the update script by visiting /update.php
5. Take the site out of maintenance mode

Note that this release specifically fixes an update path issue from 8.1.3 to 8.1.4, so sites experiencing that specific problem should benefit from this update.

Upgrade Recommendations

Recommended for all Drupal 8.1.x sites

This release contains important bug fixes and is recommended for all sites running Drupal 8.1.x. In particular:

• Sites experiencing issues when updating from 8.1.3 to 8.1.4 should upgrade to this release immediately
• Sites with complex configuration dependencies may benefit from the ConfigDependencyManager fix
• All sites will benefit from the simplified server requirements with the removal of the Twig C extension requirement

As this is a maintenance release, the upgrade process should be straightforward with minimal risk.

Bug Fixes

Critical Update Path Fix

• Fixed issue #2761865: Update from 8.1.3 to 8.1.4 breaks site seemingly permanently. This resolves a critical issue that could cause sites to break during the update process.

Configuration System Fix

• Fixed issue #2762549: Array was modified by the user comparison function in ConfigDependencyManager::getDependentEntities(). This resolves potential issues with configuration dependency management.

Documentation Corrections

• Fixed issue #2738891: Instructions for adding CKEditor stylesheets are now updated with current best practices.
• Fixed issue #2760585: Corrected typo in comments in Classy theme's page.html.twig template.

New Features

No significant new features were added in this maintenance release. This update focuses on bug fixes, documentation improvements, and performance enhancements.

Security Updates

No security fixes were included in this release. For the latest security information, always refer to the official Drupal Security Advisories.

Performance Improvements

Twig Performance Enhancement

• Removed the Twig C extension requirement (issue #2568247) as it was no longer providing significant performance benefits for modern PHP versions. This change simplifies server requirements while maintaining good performance with modern PHP implementations.

Impact Summary

Drupal 8.1.6 is primarily a maintenance release that addresses several important issues. The most significant impact comes from fixing a critical update path issue that could break sites when updating from 8.1.3 to 8.1.4. This ensures better stability for the update process.

The removal of the Twig C extension requirement simplifies server requirements while maintaining good performance with modern PHP versions. This makes Drupal more accessible on various hosting environments without compromising performance.

Documentation improvements for CKEditor stylesheets and fixes for the Classy theme template comments enhance the developer experience. The fix for the ConfigDependencyManager improves the reliability of configuration management.

Overall, this release improves stability, documentation accuracy, and simplifies requirements without introducing breaking changes.