Summary

Fixes #7190.

This is a fallback PR based on the existing work in #7191, because pushing a follow-up commit to Mostafa-Khairy0:fix-fetch-timeout-safari was denied by GitHub. Credit goes to @Mostafa-Khairy0 for the original PR and to @jasonsaayman for narrowing the fix to axios' composed abort reason.

What changed

• Normalize fetch abort failures through composedSignal.reason before reading the caught error. This avoids Safari DOMException-like getter failures.
• Preserve timeout semantics as AxiosError with ETIMEDOUT.
• Preserve user cancellation as CanceledError / ERR_CANCELED instead of reclassifying it as timeout.
• Update the Bun fetch timeout smoke expectation to ETIMEDOUT, matching the fetch adapter timeout path.

Tests

• npm run test:vitest:unit -- tests/unit/adapters/fetch.test.js
• npm run test:vitest:unit -- tests/unit/composeSignals.test.js
• npm run build

npm run test:smoke:bun was not run locally because Bun is not installed in this environment.

Summary by cubic

Fixes Safari abort handling in the fetch adapter by preserving the composed abort reason and correctly distinguishing timeouts (ETIMEDOUT) from user cancels (ERR_CANCELED). This prevents DOMException getter crashes and makes error behavior consistent across runtimes.

Description

• Summary of changes

  • Read abort reason from composedSignal.reason before inspecting the thrown error.
  • Timeouts now throw AxiosError with code ETIMEDOUT; user cancels throw CanceledError with ERR_CANCELED.
  • Attach the original thrown error as cause when propagating the composed abort reason, and keep config/request on the error.
  • Updated Bun smoke test to expect ETIMEDOUT for fetch adapter timeouts.

• Reasoning

  • Safari can reject with DOMException-like objects whose getters throw; touching name/message can crash.
  • Using the composed signal preserves timeout vs cancel semantics safely.

• Additional context

  • Aligns the fetch adapter’s timeout path with existing timeout semantics in axios.

Docs

• Update /docs/ to clarify:
  • fetch adapter timeout errors use ETIMEDOUT.
  • Cancellation errors use ERR_CANCELED and are detectable via axios.isCancel(err) or CanceledError.
  • Note Safari’s DOMException behavior and the adapter’s normalization.

Testing

• Added unit tests in tests/unit/adapters/fetch.test.js:
  • Timeout returns AxiosError with ETIMEDOUT.
  • User-initiated abort returns CanceledError (ERR_CANCELED) even with Safari-like broken DOMException.
  • Broken DOMException on abort during timeout surfaces as ETIMEDOUT.
• Hardened unit tests by using ephemeral ports to reduce flakiness.
• Updated smoke test in tests/smoke/bun/tests/timeout.smoke.test.ts to expect ETIMEDOUT.
• No further tests needed.

Semantic version impact

• Patch: bug fix in fetch adapter error normalization.
• Note: timeout code for the fetch adapter is now ETIMEDOUT (was ECONNABORTED in some cases). Consumers checking for timeout by code should handle ETIMEDOUT.

^{Written for commit 3ff04a2. Summary will update on new commits. Review in cubic}