Deno v1.25.2 — Release Notes & Engineering Impact

Source available — automated, not human-reviewed

Component: deno · Channel: stable. Automated analysis, not a compatibility certification. How this works.

Analysis updated: 2026-11-01.

Breaking-change evidence from the source

- BREAKING(unstable): remove --compat mode (#15678)

Read the original context ↗

Source flags breaking changes — review applicability

📄 .MD

✨ Features 3 ⚡ Improvements 3 🔧 Bug Fixes 6 ⚠️ Breaking & Deprecations 1

⚡ Executive Summary (TL;DR)

Deno v1.25.2. Source highlight: BREAKING(unstable): remove --compat mode (#15678)

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Who Does This Impact? (Role-Based Analysis)

💻 Software Engineers & Devs

Check the source notes against the package and APIs you use before upgrading.

📊 Product & Engineering Leads

Use the documented changes to assess relevance to your product; release frequency alone is not a quality measure.

⚙️ DevOps & Security

Verify the target version, runtime requirements and rollback procedure in the official documentation.

⚠️ Breaking Changes & Deprecations (1)

- BREAKING(unstable): remove --compat mode (#15678)

✨ New Features & Capabilities (3)

feat(ext/ffi): Implement FFI fast-call trampoline with Dynasmrt (#15305)
feat(ext/ffi): Support bool FFI type (#15754)
feat(serde_v8): Support StringObject as unit enum variant (#15715)

⚡ Performance & Enhancements (3)

perf(ops): inline &[u8] arguments and enable fast API (#15731)
perf(runtime): flatten arguments for write_file ops (#15776)
perf(runtime): short-circuit `queue_async_op` for Poll::Ready (#15773)

🔧 Bug Fixes & Patches (6)

fix(bench): make sure bytes/response is equal (#15763)
fix(cli): Fix panic when providing invalid urls to --reload (#15784)
fix(cli): allow using file resource synchronously while being used async
fix(cli/repl): await Promise.any([])... (#15623)
fix(core): Register external references for imports to the SnapshotCreator
fix(core): make errors more resistant to tampering (#15789)

📄 View Raw Release Notes (Original Developer Log)

### 1.25.2 / 2022.09.09 - BREAKING(unstable): remove --compat mode (#15678) - feat(ext/ffi): Implement FFI fast-call trampoline with Dynasmrt (#15305) - feat(ext/ffi): Support bool FFI type (#15754) - feat(serde_v8): Support StringObject as unit enum variant (#15715) - fix(bench): make sure bytes/response is equal (#15763) - fix(cli): Fix panic when providing invalid urls to --reload (#15784) - fix(cli): allow using file resource synchronously while being used async (#15747) - fix(cli/repl): await Promise.any([])... (#15623) - fix(core): Register external references for imports to the SnapshotCreator (#15621) - fix(core): make errors more resistant to tampering (#15789) - fix(core): opAsync leaks a promise on type error (#15795) - fix(docs): add missing categories for unstable (#15807) - fix(docs): change category for Deno.Process to "Sub Process" (#15812) - fix(ext/flash): use utf8 length as Content-Length (#15793) - fix(ext/timers): create primordial `eval` (#15110) - fix(init): suppress info logs when using quiet mode (#15741) - fix(npm): add more context to errors when file doesn't exist (#15749) - fix(npm): conditional exports in npm: specifiers (#15778) - fix(npm): correct exact matching of pre-release versions (#15745) - fix(npm): recursive translation of reexports, remove window global in node code (#15806) - fix(npm): respect `latest` dist tag for getting current version (#15746) - fix(ops): use qualified borrow in op macro (#15769) - fix(repl): don't terminate on unhandled error events (#15548) - fix(test): unflake wasm_unreachable test (#15794) - fix(watch): ignore unload errors on drop (#15782) - fix: upgrade deno_ast to 0.19 (#15808) - perf(ops): inline &[u8] arguments and enable fast API (#15731) - perf(runtime): flatten arguments for write_file ops (#15776) - perf(runtime): short-circuit `queue_async_op` for Poll::Ready (#15773)

← Older Version Deno v1.25.1 Newer Version → Deno v1.25.3