claude-code - 💡(How to fix) Fix --resume crashes with 'UKH is not a function' on session load (2.1.120 regression) [1 participants]

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anthropics/claude-code#53094Fetched 2026-04-25 06:12:30
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In Claude Code 2.1.120, --resume crashes when loading any saved session. The session list renders fine (titles + previews visible), but selecting a session — or passing a UUID directly via claude --resume <uuid> — throws UKH is not a function and exits.

Error Message

The error string UKH is not a function is a minified function name, so the failing call site is opaque from the user side — but the fact that it triggers specifically on saved-session load (list renders fine, fresh sessions work fine) points to the resume/replay code path.

Root Cause

In Claude Code 2.1.120, --resume crashes when loading any saved session. The session list renders fine (titles + previews visible), but selecting a session — or passing a UUID directly via claude --resume <uuid> — throws UKH is not a function and exits.

Fix Action

Workaround

  • Pin to 2.1.119: ln -sfn ~/.local/share/claude/versions/2.1.119 ~/.local/bin/claude
  • Disable autoupdater so it doesn't bump back: "env": { "DISABLE_AUTOUPDATER": "1" } in ~/.claude/settings.json
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Bug Report — Claude Code 2.1.120 --resume regression

Title: --resume crashes with "UKH is not a function" when selecting a saved session in 2.1.120


Summary

In Claude Code 2.1.120, --resume crashes when loading any saved session. The session list renders fine (titles + previews visible), but selecting a session — or passing a UUID directly via claude --resume <uuid> — throws UKH is not a function and exits.

Repro

  1. Have any saved session on disk under ~/.claude/projects/<project>/<uuid>.jsonl
  2. claude --resume
  3. Pick a session from the list (or run claude --resume <uuid> directly)
  4. Crash with UKH is not a function

The crash happens during transcript replay, before MCPs initialize — reproducible with no MCP servers configured.

Expected

Session loads and is ready to continue.

Confirmed regression vs 2.1.119

Rolling the symlink back to 2.1.119 and rerunning the same --resume <uuid> against the same .jsonl files loads cleanly. Same shell, same env, same project, same transcripts. Only the binary version differs.

Workaround

  • Pin to 2.1.119: ln -sfn ~/.local/share/claude/versions/2.1.119 ~/.local/bin/claude
  • Disable autoupdater so it doesn't bump back: "env": { "DISABLE_AUTOUPDATER": "1" } in ~/.claude/settings.json

Environment

  • Claude Code: 2.1.120 (broken) / 2.1.119 (works)
  • Platform: WSL2, Ubuntu 22.04.5, kernel 5.15.167.4-microsoft-standard-WSL2
  • Architecture: x86_64
  • Install: standalone (~/.local/share/claude/versions/)

Notes

The error string UKH is not a function is a minified function name, so the failing call site is opaque from the user side — but the fact that it triggers specifically on saved-session load (list renders fine, fresh sessions work fine) points to the resume/replay code path.

extent analysis

TL;DR

The most likely fix is to pin the Claude Code version to 2.1.119 until the issue in 2.1.120 is resolved.

Guidance

  • The issue seems to be related to the --resume feature in Claude Code 2.1.120, which crashes when loading a saved session.
  • To verify the issue, try loading a saved session using claude --resume <uuid> and check if it crashes with the UKH is not a function error.
  • As a temporary workaround, pin the version to 2.1.119 using the provided command: ln -sfn ~/.local/share/claude/versions/2.1.119 ~/.local/bin/claude.
  • Additionally, disable the autoupdater by adding "env": { "DISABLE_AUTOUPDATER": "1" } to ~/.claude/settings.json to prevent the version from being updated automatically.

Example

No code snippet is provided as it's not necessary for this specific issue.

Notes

The error message UKH is not a function is likely a minified function name, making it difficult to identify the exact cause without more information.

Recommendation

Apply the workaround by pinning the version to 2.1.119 until the issue in 2.1.120 is resolved, as it has been confirmed to work in the previous version.

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