eZ Publish Backwards Compatibility and where to find information
Inside eZ Publish 4.1.0 there is a new documentation directory listing all backwards compatibility (BC) changes for this release. This directory is located under 'doc/bc' folder within the eZ Publish root. Here you can find important information about BC changes which help with the upgrade process from previous eZ Publish versions, as well with your extensions.
eZPedia.org provides additional documentation on BC changes.
If you are wondering about BC changes with the 4.0.x series, please take a look here: "eZ Publish 4.0: post-release notes"
