Migrating from PHP 5.5.x to PHP 5.6.x

• Backward incompatible changes
• New features
• Deprecated features in PHP 5.6.x
• Changed functions
• New functions
• OpenSSL changes in PHP 5.6.x
• Other changes to extensions
• New global constants

Most improvements in PHP 5.6.x have no impact on existing code. There are a few incompatibilities and new features that should be considered, and code should be tested before switching PHP versions in production environments.