[BUG] Claude Code 2.1.27 freezes after first message - regression from 2.1.25

Description

Claude Code 2.1.27 freezes after sending the first message. The UI shows "Frolicking..." (thinking animation) and then becomes completely unresponsive. Downgrading to 2.1.25 immediately fixes the issue.

Environment

OS: Windows 11 + WSL2 (Ubuntu)
Claude Code Version: 2.1.27 (broken), 2.1.25 (works)
Terminal: Windows Terminal, Zed terminal, standard WSL terminal
Shell: bash with custom .bashrc

Steps to Reproduce

Install/update to Claude Code 2.1.27
Run claude in any directory
Type "hi" and press Enter
Observe: Shows "Frolicking..." then freezes indefinitely

Expected Behavior

Claude should respond to the message.

Actual Behavior

UI freezes after showing "Frolicking..."
No response is displayed
Terminal becomes unresponsive (can't Ctrl+C)
When terminal is closed, Claude process becomes orphaned and runs at ~95% CPU

Workaround

Downgrade to 2.1.25:

ln -sf ~/.local/share/claude/versions/2.1.25 ~/.local/bin/claude

Suspected Cause

Based on the 2.1.27 changelog, one of these changes may be responsible:

"Fixed bash command execution failing for users with .bashrc files"
"Fixed console windows flashing when spawning child processes"

The user has a complex .bashrc with custom functions and aliases.

Additional Context

Plugins enabled/disabled makes no difference
Happens on both Windows filesystem (/mnt/c/) and Linux filesystem (~/)
Large session files (>50MB) were ruled out as the cause
CPU does not spike to 99% during freeze (stays around 18%)
The session that was already running before the update continues to work fine
Only new sessions freeze

Diagnostic Info

Platform: WSL2 (Linux 6.6.87.2-microsoft-standard-WSL2)
Node: v22.22.0
Claude Code: 2.1.27 (broken) / 2.1.25 (works)

Found 3 possible duplicate issues:

[BUG] Regression in 2.1.27: Infinite CPU loop on project startup #22057
[BUG] Claude Code v2.1.27 freezes with 100% CPU on Synology NAS (Linux 4.4 kernel) — v2.1.25 works fine #22097
CLI hangs at 99% CPU on startup with large session .jsonl files #22041

This issue will be automatically closed as a duplicate in 3 days.

If your issue is a duplicate, please close it and 👍 the existing issue instead
To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

Same issue here on MacOS

rm -rf ~/.claude/projects/the-project-where-the-freeze-happened mitigates the issue for me, and then it comes back again an hour later, also on 2.1.27

same issue on linux

same issue on macos

Confirming this issue on Ubuntu 24.04 LTS (Hetzner VPS, CX32 - 4 vCPU, 8 GB RAM).

Environment

OS: Ubuntu 24.04.3 LTS (headless server, SSH access via Termius)
Node.js: v22.21.1 (via NVM)
Claude Code: 2.1.27 (broken) → 2.1.25 (works)
Installation: npm global (via NVM)
Auth: OAuth (claude.ai subscription)

Symptoms (identical to OP)

Session starts normally, user sends first message
TUI shows thinking animation ("Creating...", "Enchanting...", "Marinating...") then freezes completely
Ctrl+C does not work, terminal becomes unresponsive
When terminal is force-closed, the claude process becomes orphaned (PPID=1) and runs at 60-99% CPU indefinitely
Multiple frozen attempts accumulated 8+ orphan processes, pushing CPU to 400% (all 4 cores maxed)

What did NOT help

Disabling all MCP servers (6 servers disabled)
Disabling all plugins
Removing custom statusLine configuration
Killing orphan processes and retrying (freeze immediately reoccurred)
Clearing project session data

What fixed it

Downgrade to 2.1.25 resolved the issue instantly. First response came back within seconds.

Important note for NVM users

If Claude Code is installed via NVM, a standard npm install -g @anthropic-ai/claude-code@2.1.25 may appear to work but the auto-updater silently upgrades it back to 2.1.27 on the next launch. The reliable approach:

# 1. Disable auto-updater FIRST (add to ~/.bashrc before NVM loads)
export DISABLE_AUTOUPDATER=1

# 2. Clean uninstall + reinstall
npm uninstall -g @anthropic-ai/claude-code
npm cache clean --force
npm install -g @anthropic-ai/claude-code@2.1.25

# 3. Verify the ACTUAL binary, not just package.json
head -5 $(npm root -g)/@anthropic-ai/claude-code/cli.js | grep Version
# Should show: // Version: 2.1.25

Also worth noting: npm install -g @version sometimes updates package.json without replacing the actual minified cli.js bundle. The head verification above catches this.

Additional observation

Sessions that were already running before the update to 2.1.27 continued to work fine (consistent with OP's report)
The freeze happens on the very first API call — debug logs show startup completing normally but no API response is ever logged
Orphan processes maintain active TCP connections to the API endpoint but never process the response

Same on MacOS 26.3

same on MacOS 26.2

Also having the issue on MacOS 26.2. I have one session running fine, but starting the second session in another terminal window, it get stuck on the first message.

+1 on Pi 5 (ARM64, 8GB). Downgrade to 2.1.25 fixed it.

Reverted to 2.1.22 to fix on Linux.

same here on WSL2. Following fixed it.
curl -fsSL https://claude.ai/install.sh | bash -s 2.1.25

1. Rollback to 2.1.25

curl -fsSL https://claude.ai/install.sh | bash -s 2.1.25

2. Prevent update to 2.1.27

rm -f ~/.local/share/claude/versions/2.1.27
chmod 555 ~/.local/share/claude/versions

3. Create smart update script

mkdir -p ~/scripts
cat > ~/scripts/claude-smart-update.sh << 'EOF'
#!/bin/bash
SKIP_VERSION="2.1.27"
CURRENT=$(readlink ~/.local/bin/claude | grep -oP '\d+.\d+.\d+')
LATEST=$(ls ~/.local/share/claude/versions/ 2>/dev/null | grep -oP '\d+.\d+.\d+' | sort -V | tail -1)

if [ "$LATEST" != "$CURRENT" ] && [ "$LATEST" != "$SKIP_VERSION" ]; then
if [ "$(printf '%s\n' "$LATEST" "$CURRENT" | sort -V | tail -1)" = "$LATEST" ]; then
chmod 755 ~/.local/share/claude/versions
curl -fsSL https://claude.ai/install.sh | bash -s "$LATEST"
NEW_VERSION=$(readlink ~/.local/bin/claude | grep -oP '\d+.\d+.\d+')
# Auto-destroy after update to 2.1.28+
if [[ "$NEW_VERSION" > "2.1.27" ]]; then
crontab -l | grep -v "claude-smart-update" | crontab -
rm -f ~/scripts/claude-smart-update.sh
fi
fi
fi
EOF
chmod +x ~/scripts/claude-smart-update.sh

4. Setup cron (every 2 hours)

(crontab -l 2>/dev/null; echo "0 */2 * * * $HOME/scripts/claude-smart-update.sh >> /tmp/claude-smart-update.log 2>&1") | crontab -

Same issue on Ubuntu 25.10 x86_64. Downgrading to 2.1.25 resolves it for now

Same issue on Mac Tahoe 26.2. Downgrading to 2.1.25 fixes it.

Same issue. Mac 15.3.1.
Downgrading to 2.1.25 did not fix it for me. Removing the project dir from ~/.claude/projects fixed it.

I've fixed this issue by moving it to 2.1.29 instead of downgrading to 2.1.25. I also cleaned a few stale project entries from ~/.claude/projects since I've renamed my project name

I've fixed this issue by moving it to 2.1.29 instead of downgrading to 2.1.25

Had the same problem, upgraded to v2.1.31 and it looks like things are working on my end. Good rec.

Issue still persists for me on v2.1.31. Deleting the project folder worked. I get the impression that something is "filling up," perhaps a cache get corrupted?

This has been happening to me fr a few weeks. Very frustrating and no serious fix yet.

Have started going back to Cursor...

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.

Navigation Menu

Repository navigation

[BUG] Claude Code 2.1.27 freezes after first message - regression from 2.1.25 #22103

Description

Environment

Steps to Reproduce

Expected Behavior

Actual Behavior

Workaround

Suspected Cause

Additional Context

Diagnostic Info

Environment

Symptoms (identical to OP)

What did NOT help

What fixed it

Important note for NVM users

Additional observation

3 remaining items

1. Rollback to 2.1.25

2. Prevent update to 2.1.27

3. Create smart update script

4. Setup cron (every 2 hours)

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

[BUG] Claude Code 2.1.27 freezes after first message - regression from 2.1.25 #22103

Description

Description

Environment

Steps to Reproduce

Expected Behavior

Actual Behavior

Workaround

Suspected Cause

Additional Context

Diagnostic Info

Activity

github-actions commented on Jan 31, 2026

kerim commented on Jan 31, 2026

sarth6 commented on Jan 31, 2026

belcaik commented on Jan 31, 2026

liuzili97 commented on Jan 31, 2026

aranej commented on Jan 31, 2026

Environment

Symptoms (identical to OP)

What did NOT help

What fixed it

Important note for NVM users

Additional observation

ZenAlexa commented on Jan 31, 2026

yeongjunyoo commented on Jan 31, 2026

tbvl commented on Jan 31, 2026

nicholas-stancio-saka commented on Jan 31, 2026

3 remaining items

Kevin-Mok commented on Jan 31, 2026

rlallen commented on Jan 31, 2026

vdp1331 commented on Jan 31, 2026

1. Rollback to 2.1.25

2. Prevent update to 2.1.27

3. Create smart update script

4. Setup cron (every 2 hours)

rupurt commented on Jan 31, 2026

mdonova33 commented on Jan 31, 2026

iraritchiemeek commented on Feb 1, 2026

srgfrancisco commented on Feb 2, 2026

jj-dominguez commented on Feb 4, 2026

mykeln commented on Feb 5, 2026

phillydoug commented on Feb 5, 2026

github-actions commented on Feb 13, 2026

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions