---
name: reference_claude_code_bun_crash_pin
description: Claude Code v2.1.114+ (Bun-based builds) segfault at startup on Windows 11 — fix is pin to 2.1.110 + DISABLE_AUTOUPDATER; unpin when upstream fix ships
type: reference
---

Claude Code v2.1.114+ ships as a Bun-compiled binary; on some Windows 11 builds (seen on
Howard-Home, Win11 build 26100, CC v2.1.207, 2026-07-13) NEW interactive sessions crash at
TUI init with `panic: Segmentation fault at address 0x3C` / "oh no: Bun has crashed".
Already-running sessions keep working (binary loaded in memory); only fresh launches die.
Tracked: anthropics/claude-code #55219 (+ matching upstream Bun issue). `--version`/`--help`
still work. It is a runtime bug inside the shipped binary — no config/cache/reinstall of the
same version helps.

**Fix (verified working 2026-07-13, Howard-Home):**
1. `npm install -g @anthropic-ai/claude-code@2.1.110` (last pure-Node build; installs fine
   even while an older session is running — the EPERM "cleanup" warning is just npm failing
   to delete the locked running exe, the install itself succeeds).
2. Pin it — in `~/.claude/settings.json` add:
   `"env": { "DISABLE_AUTOUPDATER": "1" }`
   NOTE: a field named `autoUpdate` does NOT exist in the settings schema (validation
   rejects it); the env-var route is the correct kill switch.
3. **Unpin when fixed:** watch issue #55219; then `npm i -g @anthropic-ai/claude-code@latest`
   and remove the env entry.

Do NOT switch to the native installer as a workaround — it is also Bun-based (same crash).