UTF8View now throws instead of aborting on huge non-UTF-8 strings (
0ea0a56)
Bun’s UTF-8 conversion path no longer hard-aborts when a string can’t be represented as UTF-8, including extreme Latin-1 inputs that previously took down the process. The change threads failure through UTF8View and adds coverage for the conversion limit.
Bun.serve restores correct pipelined response flushing (86e3c75, 37c2892)
Responses completed earlier in the same read are now sent before later JavaScript handlers run, fixing both the performance regression and the response-loss edge cases introduced by the prior corking behavior. This brings Bun.serve’s pipelined HTTP/1.1 handling back in line with expected ordering and makes the behavior more robust when handlers stop or terminate sockets mid-read.
YAML.stringify fixes alias reuse and block layout (f59e351, d9b0bf7)
Bun.YAML.stringify now keeps visited collections alive so garbage collection can’t recycle their addresses into incorrect aliases, and block-style output is corrected for trailing spaces, empty collections, and indentation alignment. These fixes address both silent data corruption and malformed YAML output.
TLS hostname handling strips IPv6 brackets before verification (81b7f41)
Bun now normalizes bracketed IPv6 literals like [::1] before TLS cert verification, SNI, proxy tunnel setup, and websocket upgrades. That prevents false certificate mismatches and aligns Bun with Node’s hostname handling.
React Compiler preserves compound-assignment values correctly (c3a107e, f3c1954, 80d35ac)
Compound assignments to locals now keep the value they store, instead of lowering into a separate read that can reorder expressions or leave stray reads behind. A related scope-pruning panic on assignments inside ?: tests is also fixed, improving both correctness and compiler stability.
Fake timers stop zero-delay rearm loops from hanging (368a6f7)
Under jest.useFakeTimers(), timers rearmed with zero delay inside a timer callback are now treated as due again in the same drain cycle. That fixes hangs in advanceTimersByTime() and runOnlyPendingTimers() for common recursive timer patterns.
HTTP/3 aborted uploads now reset streams properly (b364c63)
Aborted fetch() uploads over HTTP/3 now send RESET_STREAM instead of finishing with FIN, so servers stop treating truncated bodies as complete requests. This also avoids collateral session failures on subsequent uploads.
process.memoryPressure no longer emits a false critical event (0963a1b)
Linux memory pressure notifications now ignore the spurious event fired by an unprivileged PSI trigger immediately after arming. That removes a recurring false-positive signal for apps that attach and detach listeners over time.
drainMicrotasks() no longer runs queued tasks (ffb316c)
The bun:jsc microtask drain now stays scoped to microtasks instead of also ticking the event-loop task queue. That prevents surprising callback nesting and matches the API’s name and intent more closely.
fs.read validates buffer type before offset (e8750e3)
fs.read/readSync now match Node’s argument validation order, throwing ERR_INVALID_ARG_TYPE for a bad buffer before complaining about the offset. This fixes a long-standing compatibility mismatch in the error surfaced to user code.
Other misc changes
- JS printer fixes: minify empty-source/data-loader crash, output-position bugs, and an infallible writer refactor (3 commits)
- Memory/allocator work: mimalloc pin updates and ASAN build flag tweak (3 commits)
- Dead-code cleanup across native bindings, HTTP2, shell, and WebView wrappers (2 commits)
- Bun.markdown performance fix removing O(depth^2) work
- CSS pseudo-element parsing fix for
::view-transition-group-children() bun:cryptoHKDF zero-length validation- Terminal leak fix on Windows spawn pipe errors
bun run/ AST hoisting fix for classes with static accessor initializers- Misc test and build-only adjustments