Claude Code 2.1.27 Freezing and CPU Issues. Heres What We Know So Far

How to Downgrade Claude Code on Mac

If you're hitting the freezing issue on 2.1.27, you can roll back to a stable version with these steps:

Download and install the desired version:

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

Symlink the installed version:

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

Verify the symlink:

ls -l ~/.local/bin/claude

Kill any running Claude processes:

pkill -9 claude

Open your settings file:

open ~/.claude/settings.json

Add this env block at the top:

{
  "env": {
    "DISABLE_AUTOUPDATER": "1"
  },
  // ... rest of your config
}

Check the version:

claude -v

Confirm auto updates are disabled:

claude doctor

You should see:

Updates
└ Auto-updates: disabled (DISABLE_AUTOUPDATER set)
└ Auto-update channel: stable 

That's it! You're locked in until Anthropic pushes a fix.

Just wanted to drop some extra info on this. Theres a GitHub issue that digs into the actual error causing this. https://github.com/anthropics/claude-code/issues/22116

Looks like the culprit is this error that shows up in the debug logs right at startup. Failed to check enabledPlatforms TypeError undefined is not an object evaluating aZ.join. It happens before MCP even initializes.

The interesting part is this error actually appears in both 2.1.27 and 2.1.23.

But in 2.1.23 it gets handled gracefully and everything continues.

In 2.1.27 it seems to cause some kind of blocking loop that spikes CPU and locks everything up.

Theres also a few related issues on GitHub that might be the same root cause.

One about the plugin command causing freezes, another about a .claude-plugin directory in your working directory triggering it, and a general regression report.

For anyone on Mac, 2.1.23 is another version you can roll back to if 2.1.25 isnt doing it for you.

You can symlink it like this:

ln -sf ~/.claude/versions/2.1.23 ~/.local/bin/claude

Hopefully Anthropic gets this sorted soon. The debug logs in that GitHub issue are pretty detailed so fingers crossed it helps them find the fix faster.