breaking change
A modification to a software interface or API that is incompatible with previous versions, requiring consumers to update their code to avoid errors.
Full Definition
A breaking change is any alteration to a public API, data contract, or system interface that causes existing client code to fail or behave differently without modification. In semantic versioning, breaking changes trigger a major version increment (e.g. 2.x.x → 3.0.0). Editors will encounter the term in changelogs, migration guides, and release notes. The term is always a two-word noun phrase ('a breaking change', 'breaking changes'); 'breaking-change' with a hyphen is appropriate only when used as a compound modifier before a noun ('a breaking-change release'). Editors must not soften 'breaking change' to 'significant change', as the former carries a precise technical meaning.
Usage
Usage note: Do not substitute 'significant change' for 'breaking change'; they are not equivalent. Hyphenate only as a compound modifier: 'a breaking-change release'.
In Context
- "The removal of the `user.name` field is a breaking change that will affect all clients on v1." — API migration guide
- "Label pull requests with 'breaking change' so the release manager can bump the major version accordingly." — Contribution guidelines