# Deno v0.40.0 — Release & Upgrade Intelligence
- **Product:** Deno (https://deno.com)
- **Version:** v0.40.0
- **Released:** Apr 08, 2020
- **Impact Score:** 7/10
- **Breaking Changes:** Source flagged
- **Canonical Analysis:** https://changelogs.us/deno/updates/v0.40.0/

## Executive Summary (TL;DR)
Deno v0.40.0. Source highlight: BREAKING: Rename 'deno fetch' subcommand to 'deno cache' (#4656)

## Breaking Changes & Deprecations
- - BREAKING: Rename 'deno fetch' subcommand to 'deno cache' (#4656)
- - BREAKING: Remove std/testing/runner.ts (#4649)

## New Features
- feat(std/flags): Pass key and value to unknown (#4637)
- feat(std/http): Respond with 400 on request parse failure (#4614)
- feat(std/node): Add exists and existsSync (#4655)
- feat: Add File support in FormData (#4632)
- feat: Expose ReadableStream and make Blob more standardized (#4581)
- feat: add --importmap flag to deno bundle (#4651)

## Bug Fixes
- fix(#4546): Added Math.trunc to toSecondsFromEpoch to conform the result to u64 (#4575)
- fix(file_server): use text/typescript instead of application/typescript (#4620)
- fix(std/testing): format bigint (#4626)
- fix: Drop headers with trailing whitespace in header name (#4642)
- fix: Fetch reference types for JS files (#4652)
- fix: Improve deno doc (#4672, #4625)