DOMException: The connection was closed is not catchable

Which project does this relate to?

Start

Describe the bug

When a client disconnects during streaming, the resulting DOMException: The connection was closed cannot be caught and floods the production server logs.

This issue often arises from bots or users closing the tab while streaming is still in progress.

Your Example Website or App

https://github.com/checkerschaf/start-domexception-aborterror

Steps to Reproduce the Bug or Issue

1. Clone the reproduction repo
2. Run bun install
3. Run bun run build
4. Start the server: bun run bun-server.ts
5. Run the script bun run reproduce-abort-error.ts in a new terminal while the server is running

Expected behavior

No errors in the server console and the streaming cancellation should be handled gracefully.

Screenshots or Videos

No response

Platform

• Start Version: 1.140.5
• Bun: 1.3.4

Additional context

Full error logs:

error: The connection was closed.
      cause: DOMException {
  line: 4174,
  column: 32,
  sourceURL: "/Users/xyz/tart-domexception-aborterror/node_modules/react-dom/cjs/react-dom-server.bun.production.js",
  stack: "@/Users/xyz/tart-domexception-aborterror/node_modules/react-dom/cjs/react-dom-server.bun.production.js:4174:32\nPromise@\n@/Users/xyz/tart-domexception-aborterror/node_modules/react-dom/cjs/react-dom-server.bun.production.js:4137:23\n@/Users/xyz/tart-domexception-aborterror/node_modules/@tanstack/react-router/dist/esm/ssr/renderRouterToStream.js:12:63\nrenderRouterToStream@/Users/xyz/tart-domexception-aborterror/node_modules/@tanstack/react-router/dist/esm/ssr/renderRouterToStream.js:5:37\n@/Users/xyz/tart-domexception-aborterror/dist/server/server.js:315:32\nprocessTicksAndRejections@",
  code: 20,
  name: "AbortError",
  message: "The connection was closed.",
  INDEX_SIZE_ERR: 1,
  DOMSTRING_SIZE_ERR: 2,
  HIERARCHY_REQUEST_ERR: 3,
  WRONG_DOCUMENT_ERR: 4,
  INVALID_CHARACTER_ERR: 5,
  NO_DATA_ALLOWED_ERR: 6,
  NO_MODIFICATION_ALLOWED_ERR: 7,
  NOT_FOUND_ERR: 8,
  NOT_SUPPORTED_ERR: 9,
  INUSE_ATTRIBUTE_ERR: 10,
  INVALID_STATE_ERR: 11,
  SYNTAX_ERR: 12,
  INVALID_MODIFICATION_ERR: 13,
  NAMESPACE_ERR: 14,
  INVALID_ACCESS_ERR: 15,
  VALIDATION_ERR: 16,
  TYPE_MISMATCH_ERR: 17,
  SECURITY_ERR: 18,
  NETWORK_ERR: 19,
  ABORT_ERR: 20,
  URL_MISMATCH_ERR: 21,
  QUOTA_EXCEEDED_ERR: 22,
  TIMEOUT_ERR: 23,
  INVALID_NODE_TYPE_ERR: 24,
  DATA_CLONE_ERR: 25,
  toString: [Function: toString],
},
     status: 500,
 statusText: undefined,
    headers: undefined,
       data: undefined,
       body: undefined,
  unhandled: true,

      at /Users/xyz/tart-domexception-aborterror/node_modules/h3-v2/dist/h3.mjs:315:41

Start with the linked reproduction repo and run bun install, bun run build, bun run bun-server.ts, then reproduce-abort-error.ts. Trace the server-side streaming path shown in the stack, including renderRouterToStream and h3-v2 handling, and rerun the reproduction; done means client disconnects are cancelled gracefully without flooding the server console with errors.