# Deno v1.27.0 — Release & Upgrade Intelligence
- **Product:** Deno (https://deno.com)
- **Version:** v1.27.0
- **Released:** Oct 27, 2022
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/deno/updates/v1.27.0/

## Executive Summary (TL;DR)
Deno v1.27.0. Source highlight: feat(core): enable --harmony-change-array-by-copy V8 flag (#16429)

## New Features
- feat(core): enable --harmony-change-array-by-copy V8 flag (#16429)
- feat(cli): check for updates in background (#15974)
- feat(cli): show error cause recursion information (#16384)
- feat(ext/ffi): Make op_ffi_ptr_of fast (#16297)
- feat(ext/net): add reuseAddress option for UDP (#13849)
- feat(ext/net): reusePort for TCP on Linux (#16398)

## Improvements
- perf(core): avoid creating global handles in `op_queue_microtask` (#16359)
- perf(core): avoid isolate slots for ModuleMap (#16409)
- perf(core): do not drive JsInspector by default (#16410)
- perf(core): don't access isolate slots for JsRuntimeState (#16376)
- perf(ext/ffi): Fast UnsafePointerView read functions (#16351)
- perf(ext/flash): optimize path response streams (#16284)

## Bug Fixes
- fix(build) assume a custom compiler will support --export-dynamic-symbol-list
- fix(cli): Fixed bug where the progress bar did not clear (#16401)
- fix(cli): do not log update checker when log level is quiet (#16433)
- fix(compile): show an error when using npm specifiers (#16430)
- fix(core) Include causes when converting anyhow errors to JS exceptions
- fix(ext/fetch): fix `size_hint` on response body resource (#16254)