# Vitest v4.0.17 — Release & Upgrade Intelligence
- **Product:** Vitest (https://vitest.dev)
- **Version:** v4.0.17
- **Released:** Jan 12, 2026
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/vitest/updates/v4.0.17/
## Executive Summary (TL;DR)
Vitest v4.0.17. Source highlight: 🚀 Experimental Features
## New Features
- Support openTelemetry for browser mode - by @hi-ogawa in https://github.com/vitest-dev/vitest/issues/9180 (1ec3a)
- Support TRACEPARENT and TRACESTATE environment variables for OpenTelemetry context propagation - by @Copilot, **hi-ogawa** and @hi-ogawa in https://github.com/vitest-dev/vitest/issues/9295 (876cb)
## Bug Fixes
- Improve asymmetric matcher diff readability by unwrapping container matchers - by @Copilot, **sheremet-va**, **hi-ogawa** and @hi-ogawa in https://github.com/vitest-dev/vitest/issues/9330 (b2ec7)
- Improve runner error when importing outside of test context - by @sheremet-va in https://github.com/vitest-dev/vitest/issues/9335 (2dd3d)
- Replace crypto.randomUUID to allow insecure environments (fix #9… - by @plusgut in https://github.com/vitest-dev/vitest/issues/9339 and https://github.com/vitest-dev/vitest/issues/9 (e6a3f)
- Handle null options in `addEventHandler` #9371 - by @ThibautMarechal in https://github.com/vitest-dev/vitest/issues/9372 and https://github.com/vitest-dev/vitest/issues/9371 (40841)
- Typo in browser.provider error - by @deammer in https://github.com/vitest-dev/vitest/issues/9394 (4b67f)
- Fix `process.env` and `import.meta.env` defines in inline project - by @hi-ogawa in https://github.com/vitest-dev/vitest/issues/9239 (b70c9)