Bug: VS Code keeps restarting / extension crash

[sebastienmascha]

Plugin Type

VSCode Extension

Cline Version

3.51.0

What happened?

VS Code’s extension host repeatedly crashes and restarts shortly after startup when the Cline extension is enabled. The extension host logs show repeated errors:

PendingMigrationError: navigator is now a global in nodejs, please see https://aka.ms/vscode-extensions/navigator

The stack traces consistently point into the Cline extension bundle (saoudrizwan.claude-dev/dist/extension.js). While this happens, VS Code becomes unstable and keeps restarting the extension host.

I expected VS Code to remain stable and for the Cline extension to activate normally without crashing the extension host.

Steps to reproduce

1. Install and enable the Cline extension.
2. Open VS Code (either locally or using Remote SSH).
3. Open any workspace or folder.
4. Within seconds, the extension host logs show repeated PendingMigrationError exceptions and the extension host restarts.

Note: Disabling or uninstalling Cline immediately stops the crash/restart loop.

Provider/Model

openrouter:anthropic/claude-sonnet-4.5

System Information

Operating System:

Occurs both locally and via VS Code Remote SSH

Observed on Linux (Ubuntu 24.04)

Hardware:

CPU: x86_64

RAM: 32 GB

GPU: NVIDIA (not required to reproduce)

VS Code / Extension details:

VS Code Server commit (remote): 585eba7c0c34fd6b30faac7c62a42050bfbc0086

Cline extension: saoudrizwan.claude-dev version 3.51.0

[linear]

CLINE-1176

[github-actions]

Thanks for the detailed report and clear reproduction steps!

Root Cause

This is a known VS Code 1.101+ compatibility issue. Starting with VS Code 1.101, the extension host now runs on Node.js versions where navigator is a read-only global. The error occurs because Cline's dependency chain includes mammoth@1.11.0, which depends on bluebird@~3.4.0. That older version of bluebird attempts to assign to the navigator global (for browser detection), which now throws PendingMigrationError since it's a protected global in Node.js 20+.

The dependency chain:

cline → mammoth@1.11.0 → bluebird@~3.4.0 (problematic)

VS Code Version Correlation

This issue is specific to VS Code 1.101+ (May 2025 release and later). The VS Code 1.101 release notes introduced support for the Node.js navigator global in extension hosts, which surfaces this incompatibility.

Recommended Fix

The Roo-Code extension encountered the identical issue and fixed it by:

1. Upgrading mammoth to ^1.9.1 or later
2. Adding an npm override to force bluebird>=3.7.2

For Cline, this would mean adding to package.json:

"overrides": {
  "bluebird": ">=3.7.2"
}

Workaround

Until a fix is released:

• Downgrade VS Code to 1.100.x or earlier, or
• Use VS Code Insiders if it has a patched version, or
• Disable Cline and wait for the next release

Related Issues

I analyzed recent PRs and releases but didn't find any Cline-specific changes that introduced this - it's purely a VS Code + Node.js version incompatibility surfacing an existing dependency issue.

SME	Reason
@canvrno	Authored PR #6991 which updated mammoth to current version
@abeatrix	Primary contributor to dependency updates
@saoudrizwan	Core maintainer

---

Possible Duplicates

• code-server compatibility broken since v3.28 - File is not defined #8381 - code-server compatibility broken since v3.28 (similar browser API incompatibility, different dependency)

No exact duplicates found - this is the first report specifically about the navigator global issue with Cline.

[ClineXDiego]

Hi @sebastienmascha, thanks!

This is caused by an undici dependency issue with newer Node.js. PR #8783 (pending) upgrades undici to 7.19.0 which should fix this.

Try updating once the next release ships. Thanks!

[ClineXDiego]

PR merged - Closing.
Please let us know if you are still experiencing issues.