backwardincompatible

Backward incompatible, commonly called a breaking change, is a modification that breaks compatibility with earlier versions of a system. It occurs when software, data formats, protocols, or hardware interfaces are changed in a way that older code, files, or configurations no longer work correctly or are misinterpreted by the new version.

Scope: The concept applies to public application programming interfaces, libraries, file formats, network protocols, data schemas, and firmware or hardware interfaces.

Common forms include removal or renaming of API elements, changes in data encoding or message structure, stricter validation, altered default behavior, or removal of deprecated features after a transition period.

Impact: Backward-incompatible changes can break existing integrations, render older data unreadable, disrupt user workflows, and increase maintenance costs for developers and operators.

Mitigation: Teams typically manage such changes with clear versioning and breaking-change notices, deprecation policies, and longer transition windows. Strategies include maintaining a compatibility shim or dual interfaces, providing migration guides and tooling, and using feature flags or opt-in behaviors.

Examples span APIs that remove or rename functions, file formats that drop fields or alter schemas, and protocols that modify message layouts or negotiation rules.

In practice, backward-incompatible changes are often avoided in minor updates and disclosed with major-version bumps to give adopters time to migrate. They require careful communication, planning, and often a transition period to minimize disruption.