# What changed in wait-on

> 12 changes in wait-on 9 from its official release notes, upgrade guides and advisories: 1 breaking, 4 new APIs and options. Each one cited. Sources checked 2026-10-18. HTML: https://unstale.sh/npm/wait-on/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## wait-on 9

### Breaking changes

- Malformed HTTP and TCP resources now fail fast. (9.2.0) — [release notes](https://github.com/jeffbski/wait-on/releases/tag/v9.2.0)

### New APIs and options

- Adds a CLI flag to accept non-2XX HTTP statuses. (9.5.0) — [release notes](https://github.com/jeffbski/wait-on/releases/tag/v9.5.0)
- A command resource is added, and command executions are serialized. (9.4.0) — [release notes](https://github.com/jeffbski/wait-on/releases/tag/v9.4.0)
- A per-attempt commandTimeout is added for command resources. (9.4.0) — [release notes](https://github.com/jeffbski/wait-on/releases/tag/v9.4.0)
- waitOn opts can now be a string or a string array, rather than only an options object. (9.3.0) — [release notes](https://github.com/jeffbski/wait-on/releases/tag/v9.3.0)

### Behavior and default changes

- Non-strict argument parsing now matches minimist parity. (9.2.0) — [release notes](https://github.com/jeffbski/wait-on/releases/tag/v9.2.0)
- The header CLI flag can be repeated. (9.2.0) — [release notes](https://github.com/jeffbski/wait-on/releases/tag/v9.2.0)

### Tooling

- TypeScript definitions are now available for wait-on. (9.3.0) — [release notes](https://github.com/jeffbski/wait-on/releases/tag/v9.3.0)

### Fixes and other changes

- The headers type now accepts number and boolean values. (9.4.1) — [release notes](https://github.com/jeffbski/wait-on/releases/tag/v9.4.1)
- Restores compatibility with @types/wait-on, including the optional callback error parameter and aliases. (9.4.1) — [release notes](https://github.com/jeffbski/wait-on/releases/tag/v9.4.1)
- TCP resources now support IPv6. (9.2.0) — [release notes](https://github.com/jeffbski/wait-on/releases/tag/v9.2.0)
- TCP and Unix sockets are destroyed after checks. (9.2.0) — [release notes](https://github.com/jeffbski/wait-on/releases/tag/v9.2.0)