This is a major release.

Breaking

• Minimum node v18
• Removes .redirect('back'), adds .back(fallback_url) @fl0w https://github.com/koajs/koa/pull/1115
• For .redirect(), don't render redirect values in anchor ref https://github.com/koajs/koa/commit/ff25eb4a7f2392df46481fe86355161067687312
• req.origin should display the origin header if it exists, not the current hostname https://github.com/koajs/koa/issues/1008. origin now aligns with the Origin header as used in CORS.
• .body=<json> should not overwrite type if type already json https://github.com/koajs/koa/issues/1120
• Remove special ENOENT support https://github.com/koajs/koa/pull/1861 - this is a big change and will require any file servers to adapt to this change for handling 404s / files not found
• Removes generator deprecation messages. Generators are no longer supported. Koa no longer asserts if generators are used. Set content-length: 0 if body is explicitly set to null @ognjenjevremovic #1528 Remove obsolete createAsyncCtxStorageMiddleware https://github.com/koajs/koa/pull/1817
• ctx.throw now requires a format of ctx.throw(status, error, properties). See: https://www.npmjs.com/package/http-errors

New

• Support custom streams @KristapsR https://github.com/koajs/koa/pull/1825
• Support WHATWG response bodies https://github.com/koajs/koa/pull/1830 @kravorkid
• Use asyncLocalStorage to get current context from app, e.g.: const ctx = app.currentContext.

Fixes

• Handle responses when socket is no longer writable @titanism @azlond https://github.com/koajs/koa/pull/1593
• fix: Do not response Content-Length if Transfer-Encoding is defined #1562 @charlyzeng
• fix: Set body to 'null' if ctx.type = 'json' and ctx.body = null #1059 @likegun
• fix: can not get currentContext in error handler (#1758) (Gxkl <gxkl203@gmail.com>)
• Fix exports.defaults in package.json https://github.com/koajs/koa/pull/1630
• Fix leaky handles in tests https://github.com/koajs/koa/pull/1838
• Fix body null checks https://github.com/koajs/koa/pull/1814
• Fix reformatting redirect URLs https://github.com/koajs/koa/pull/1805 https://github.com/koajs/koa/pull/1804
• Fix passing ctx in error handler https://github.com/koajs/koa/pull/1758
• Avoid redos on host and protocol getter

Refactors

• Replace node query string with URLSearchParams https://github.com/koajs/koa/pull/1828 @kravorkid

Dependencies

• bump type-is@2
• bump http-errors@2
• bump cookies@0.9.1
• bump statuses@2
• bump supertest@7