claude-code - 💡(How to fix) Fix 2.1.120: TypeError "UKH is not a function" crashes `claude --resume` on startup [6 comments, 6 participants]

patunz · 2026-04-24T22:58:43Z

[claude-code] What's happening On Claude Code 2.1.120 Linux, standalone Bun-bundled binary , running claude --resume crashes immediately with: ERROR UKH is not… ## Fix / Workaround ## Workaround that worked Rollback to **2.1.119** (binary still cached locally under `~/.local/share/claude/versions/2.1.119`) — `--resume` works again. ## What's happening On Claude Code **2.1.120** (Linux, standalone Bun-bundled binary), running `claude --resume` crashes immediately with: ``` ERROR UKH is not a function. (In 'UKH(K)', 'UKH' is undefined) /$bunfs/root/src/entrypoints/cli.js:9247:5663 ``` `claude` (no flags) starts a fresh session normally. Only `--resume` (and likely `--continue`) triggers the crash. ## Repro 1. Use 2.1.120 on Linux. 2. From any directory with prior sessions, run `claude --resume`. 3. Crash before the picker appears. ## Tried, did NOT help - Killing an orphaned `claude --resume` process from a previously SSH-disconnected session (cleaned the lock under `~/.claude/sessions/`), but `--resume` still crashed. - `CLAUDE_CODE_DISABLE_CRON=1 claude --resume` — same crash. So although the surrounding minified code shows `useScheduledTasks` (`Av5`), the actual undefined symbol `UKH` is somewhere else on the resume init path. ## Workaround that worked Rollback to **2.1.119** (binary still cached locally under `~/.local/share/claude/versions/2.1.119`) — `--resume` works again. ## Likely cause Looks like a bundle hoisting / lazy-init regression on the resume code path. Surrounding code uses the pattern `\$v5=(NmH(),S6(kmH))` and `_v5=(NmH(),S6(kmH))` (lazy module getters). Something in that chain resolves to \`undefined\` and is then invoked as a function. ## Surrounding minified code (from the error frame) ```js var \$v5,sv4=1000,qv5=300,Kv5=5000; var FC6=T(()=>{L\$();V\$();Tp();zb();av4();\$\$();oN();\$v5=(NmH(),S6(kmH))}); var KV4={};X\$(KV4,{useScheduledTasks:()=>Av5}); function Av5({isLoading:H,assistantMode:\$,setMessages:q}){ let K=QD8.useRef(H);K.current=H; let _=B9(),A=F6(),z=Ww(); QD8.useEffect(()=>{ if(!TZ()||R6())return; ... let O=BC6({onFire:f,onFireTask:(M)=>{...},isLoading:()=>K.current,assistantMode:\$,getJitterConfig:t5H,isKilled:()=>!TZ(),getExtraTasks:\$V4&&Y?()=>\$V4.getRoutineCronTasks(Z_(),Y):void 0}); return O.start(),()=>{O.stop()} },[\$,q,_.getState,z]) } ... var QD8,_v5,\$V4=null; var _V4=T(()=>{ES();L\$();h6();uT();eI();Yb();C4\$();FC6();zb();\$\$();Q3();D6();K_H();QD8=u(JH(),1),_v5=(NmH(),S6(kmH))}); ``` ## Env - Claude Code **2.1.120** - Linux 6.17.0-19-generic, bash - Standalone install (\`~/.local/share/claude/versions/2.1.120\`)

claude-code2026-04-24 22:58:43

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anthropics/claude-code#53044•Fetched 2026-04-25 06:13:52

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Error Message

ERROR UKH is not a function. (In 'UKH(K)', 'UKH' is undefined)

Surrounding minified code (from the error frame)

Fix Action

Fix / Workaround

Workaround that worked

Rollback to 2.1.119 (binary still cached locally under ~/.local/share/claude/versions/2.1.119) — --resume works again.

Code Example

ERROR  UKH is not a function. (In 'UKH(K)', 'UKH' is undefined)
/$bunfs/root/src/entrypoints/cli.js:9247:5663

---

var \$v5,sv4=1000,qv5=300,Kv5=5000;
var FC6=T(()=>{L\$();V\$();Tp();zb();av4();\$\$();oN();\$v5=(NmH(),S6(kmH))});
var KV4={};X\$(KV4,{useScheduledTasks:()=>Av5});
function Av5({isLoading:H,assistantMode:\$,setMessages:q}){
  let K=QD8.useRef(H);K.current=H;
  let _=B9(),A=F6(),z=Ww();
  QD8.useEffect(()=>{
    if(!TZ()||R6())return;
    ...
    let O=BC6({onFire:f,onFireTask:(M)=>{...},isLoading:()=>K.current,assistantMode:\$,getJitterConfig:t5H,isKilled:()=>!TZ(),getExtraTasks:\$V4&&Y?()=>\$V4.getRoutineCronTasks(Z_(),Y):void 0});
    return O.start(),()=>{O.stop()}
  },[\$,q,_.getState,z])
}
...
var QD8,_v5,\$V4=null;
var _V4=T(()=>{ES();L\$();h6();uT();eI();Yb();C4\$();FC6();zb();\$\$();Q3();D6();K_H();QD8=u(JH(),1),_v5=(NmH(),S6(kmH))});

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What's happening

On Claude Code 2.1.120 (Linux, standalone Bun-bundled binary), running claude --resume crashes immediately with:

ERROR  UKH is not a function. (In 'UKH(K)', 'UKH' is undefined)
/$bunfs/root/src/entrypoints/cli.js:9247:5663

claude (no flags) starts a fresh session normally. Only --resume (and likely --continue) triggers the crash.

Repro

Use 2.1.120 on Linux.
From any directory with prior sessions, run claude --resume.
Crash before the picker appears.

Tried, did NOT help

Killing an orphaned claude --resume process from a previously SSH-disconnected session (cleaned the lock under ~/.claude/sessions/), but --resume still crashed.
CLAUDE_CODE_DISABLE_CRON=1 claude --resume — same crash. So although the surrounding minified code shows useScheduledTasks (Av5), the actual undefined symbol UKH is somewhere else on the resume init path.

Workaround that worked

Rollback to 2.1.119 (binary still cached locally under ~/.local/share/claude/versions/2.1.119) — --resume works again.

Likely cause

Looks like a bundle hoisting / lazy-init regression on the resume code path. Surrounding code uses the pattern \$v5=(NmH(),S6(kmH)) and _v5=(NmH(),S6(kmH)) (lazy module getters). Something in that chain resolves to `undefined` and is then invoked as a function.

Surrounding minified code (from the error frame)

var \$v5,sv4=1000,qv5=300,Kv5=5000;
var FC6=T(()=>{L\$();V\$();Tp();zb();av4();\$\$();oN();\$v5=(NmH(),S6(kmH))});
var KV4={};X\$(KV4,{useScheduledTasks:()=>Av5});
function Av5({isLoading:H,assistantMode:\$,setMessages:q}){
  let K=QD8.useRef(H);K.current=H;
  let _=B9(),A=F6(),z=Ww();
  QD8.useEffect(()=>{
    if(!TZ()||R6())return;
    ...
    let O=BC6({onFire:f,onFireTask:(M)=>{...},isLoading:()=>K.current,assistantMode:\$,getJitterConfig:t5H,isKilled:()=>!TZ(),getExtraTasks:\$V4&&Y?()=>\$V4.getRoutineCronTasks(Z_(),Y):void 0});
    return O.start(),()=>{O.stop()}
  },[\$,q,_.getState,z])
}
...
var QD8,_v5,\$V4=null;
var _V4=T(()=>{ES();L\$();h6();uT();eI();Yb();C4\$();FC6();zb();\$\$();Q3();D6();K_H();QD8=u(JH(),1),_v5=(NmH(),S6(kmH))});

Env

Claude Code 2.1.120
Linux 6.17.0-19-generic, bash
Standalone install (`~/.local/share/claude/versions/2.1.120`)

extent analysis

TL;DR

The most likely fix is to rollback to version 2.1.119 until the bundle hoisting/lazy-init regression on the resume code path is resolved.

Guidance

The error message UKH is not a function suggests that the UKH symbol is undefined when the --resume flag is used, indicating a potential issue with the lazy module getters in the surrounding code.
The fact that rolling back to 2.1.119 resolves the issue implies that the problem is specific to version 2.1.120.
To further troubleshoot, you can try to identify the specific code changes between 2.1.119 and 2.1.120 that may be causing the issue.
Consider reporting the issue to the Claude Code developers, providing the detailed error message and reproduction steps, to help them identify and fix the root cause.

Example

No code snippet is provided as the issue is related to a specific version of the Claude Code binary and the surrounding minified code is not easily modifiable.

Notes

The provided workaround of rolling back to 2.1.119 may not be a long-term solution, and the root cause of the issue should be investigated and addressed to ensure stability and functionality of the --resume feature.

Recommendation

Apply the workaround by rolling back to version 2.1.119 until a fixed version of Claude Code is released, as it is the most straightforward way to resolve the issue in the short term.

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claude-code - 💡(How to fix) Fix 2.1.120: TypeError "UKH is not a function" crashes `claude --resume` on startup [6 comments, 6 participants]

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Error Message

Surrounding minified code (from the error frame)

Fix Action

Fix / Workaround

Workaround that worked

Code Example

What's happening

Repro

Tried, did NOT help

Workaround that worked

Likely cause

Surrounding minified code (from the error frame)

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claude-code - 💡(How to fix) Fix 2.1.120: TypeError "UKH is not a function" crashes `claude --resume` on startup [6 comments, 6 participants]

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Error Message

Surrounding minified code (from the error frame)

Fix Action

Fix / Workaround

Workaround that worked

Code Example

What's happening

Repro

Tried, did NOT help

Workaround that worked

Likely cause

Surrounding minified code (from the error frame)

Env

extent analysis

TL;DR

Guidance

Example

Notes

Recommendation

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