Updated: Nov 7, 6:47 PM ET

Bun

Known bugs and feature requests, from its public GitHub issues.

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Oct 25Nov 7, 2026Oct 25 to Nov 7, 2026: 229 reports

Whole days, US Eastern time.

Bugs191 in the rangeTop 5

9 bun lint missing or inconsistent“Stable 1.4.4+38afee6c8 has no bun lint (it prints error: Script not found "lint").” No workaround yet
3 Empty Bun.write truncates output“An empty write to piped stdout/stderr should write zero bytes and resolve successfully, without attempting to truncate the pipe.” No workaround yet
2 clearAllTimers() throws“When importing vi from vitest, vi.clearAllTimers() throws if fake timers are inactive.” No workaround yet
2 Startup slows in large directories“Startup time should not depend on how many unrelated files sit next to the script or in ancestor directories.” Has a workaround
2 Extra stdio fd double close“If the number was reused in between, the second close hits an unrelated fd.” No workaround yet
2 Bun check reports TS2322 tsc accepts on deeply nested types“Possibly the same cause as #46998 (deep comparisons are cut off at different depths than tsc).” No workaround yet
1 No TLS alert on rejection“When a TLS client rejects the server's certificate, it must send a fatal alert before closing.” No workaround yet
1 WebView navigate() never settles“The navigate slot stays full, so every later navigate() throws Invalid state: a navigation is already pending.” No workaround yet
1 writeFile leaves stale trailing bytesWhen the final truncation fails, as with ENOSPC or a mapped view on Windows, the old tail of the file stays in place. No workaround yet
1 Globals retained after addon load“Memory grows linearly with the number of files until the worker runs out of RAM.” No workaround yet
1 Script shadows built-in check“In a project whose package.json has "check": "vp check" (honojs/hono at 588ec13), bun check runs that script instead of the built-in type checker.” Has a workaround
1 Mapped NoInfer tuple rejected“The error says Bun mapped every property of the tuple, toString included, instead of its elements. tsc 7.0.2 and tsc 5.9.3 accept the file.” No workaround yet
1 Parameterized queries fail reading int4[] and float4[] arrays“The binary array decoder for int4[] / float4[] appears to read one dimension only.” Has a workaround
1 Failing matcher passes silently“1.4.2: after ~40 s, expect(...).toBeNull() returns without throwing, so the assertion silently passes.” No workaround yet
0 Brotli decoder missing CVE fixReached by default from fetch() on any Content-Encoding: br response, plus node:zlib and DecompressionStream("brotli"). No workaround yet
0 Vitest jsdom worker fails to start“So something in jsdom@30.1.0 (vs 30.0.1, which works) trips Bun's EventTarget brand check when vitest installs its jsdom globals.” Has a workaround
0 Snapshots serialize entire DOM graph“Bun recursively walks and serializes the entire JSDOM internal object graph (including Symbol(impl)).” No workaround yet
0 setImmediate hops stall inside expect().resolves/.rejects with open I/O“The same code awaited directly runs each hop in well under a millisecond.” No workaround yet
0 Async realpath drops drive root slash“A Windows drive root is the one path fs.promises.realpath gets wrong: it comes back drive-relative (C:) instead of C:\.” No workaround yet
0 Exports dropped with export *“Under vitest on Bun the module namespace has the export * names and default, but not z — the re-exported namespace binding is dropped.” No workaround yet
0 realpathSync fails on Unix sockets“EOPNOTSUPP: unknown error, realpath '/var/run/mDNSResponder'” No workaround yet
0 File type ignores part Content-Type“The part header explicitly says Content-Type: image/png, but the parsed File.type is application/octet-stream.” No workaround yet
0 Panic on thread EAGAIN“Like Node.js: child_process.spawn/spawnSync report EAGAIN as an error the program can handle, and an idle process keeps running.” No workaround yet
0 expect resolves/rejects hangs“expect(value).rejects never settles when value is a thenable that starts its work inside an overridden then().” No workaround yet
0 Slow v8.getHeapStatistics()“v8.getHeapStatistics() should take constant time regardless of the heap size” No workaround yet
0 UDP error handler signature mismatch“A handler written from the declaration gets the error as socket and undefined as error.” No workaround yet
0 Parallel coverage under-reported“Coverage from the workers should be merged.” No workaround yet
0 captureStackTrace throws with wrapper“Only the combination of the two fails: the default Error.prepareStackTrace, when a wrapper calls it, rejects objects that are not real errors.” No workaround yet
0 Check reports TS2615 unlike tsc“bun check reports TS2615 on this file, and tsc 7.0.2 reports no errors.” No workaround yet
0 Preload default timeout ignored“In directory-form runs, only the first file's tests get the preload timeout.” Has a workaround
0 process.hrtime starts near zero“process.hrtime.bigint() (and process.hrtime()) inside a Worker counts from that worker's own start rather than from the origin the main thread uses.” No workaround yet
0 Parallel GC markers slow workloads“Each worker does the same fixed amount of work: it allocates short-lived objects holding fresh strings.” Has a workaround
0 Symlink binaries not executable“bash: ./node_modules/.bin/cowsay: Permission denied” No workaround yet
0 Type checking differs from 7.0.2“bun check accepts Box<string> as Box<number> when T is used 100 object levels deep. tsc 7.0.2 rejects it.” No workaround yet
0 Missing TS2540 for readonly intersection“tsc keeps the property read-only when the writable member of the intersection is a mapped type that removes readonly.” No workaround yet
0 Shell completions break on Bash 3.2 and ignore --cwd“Missing --cwd awareness: Completions only inspect $PWD for scripts, packages, and binaries, completely ignoring --cwd <dir> and --cwd=<dir>.” No workaround yet
0 WriteStream ignores overridden _write“The interactive menu appeared, then failed with the EPIPE error shown above.” No workaround yet
0 Long bun test --isolate runs crash with SIGILL mid-run“Symptom: bun test --isolate <corpus> (~650 test files, ~12.4k tests, ~5.4M expect calls) dies with SIGILL / exit code 132 partway through the corpus.” Has a workaround
0 Defender scans slow cache use“I managed to debug (with AI help) that this was mainly due to Windows Defender scanning Bun's runtime cache folder during imports.” Has a workaround

Feature requests38 in the rangeTop 5

Reports 229

Bugs 191

Requests 38

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Bun

Bugs191 in the rangeTop 5

Feature requests38 in the rangeTop 5

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