[Regression] Cowork OAuth fails with ERR_CONNECTION_RESET on macOS 26.2 after update to v1.2.234

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Cowork fails to start after updating Claude Desktop on April 2. Regular chat works fine. Cowork worked before this update.

Auto-update also fails with TLS error (code -1200, NSURLErrorDomain).

What Should Happen?

Cowork should start a session successfully, as it did before updating to v1.2.234.

The OAuth exchange with console.anthropic.com should complete without TLS errors. Auto-update should also work normally.

Error Messages/Logs

From ~/Library/Logs/Claude/main.log:

2026-04-03 23:16:19 [warn] [oauth] network error on fetch, flushing connection pool and retrying: net::ERR_CONNECTION_RESET
2026-04-03 23:16:19 [error] oauth authorize network error: net::ERR_CONNECTION_RESET
2026-04-03 23:16:19 [info] [oauth] failed to obtain oauth token (network_error): net::ERR_CONNECTION_RESET
2026-04-03 23:16:19 [error] Cannot start session: oauth failed (network_error): net::ERR_CONNECTION_RESET
2026-04-03 23:16:19 [error] Session initialization failed: Unable to start session. Check your internet connection and try again.

2026-04-03 23:16:38 [error] Auto-update error: A TLS error caused the secure connection to fail.
code: -1200, domain: NSURLErrorDomain

From ~/Library/Logs/Claude/cowork_vm_node.log (VM starts fine):

2026-04-03 22:06:08 [info] [VM] API reachability: REACHABLE
2026-04-03 22:06:08 [info] [VM:start] Startup complete, total time: 7396ms

Notes:
- curl to api.anthropic.com and console.anthropic.com works fine from terminal (TLS ok, Google Trust Services cert)
- Failure is specifically in Electron's TLS stack during the OAuth exchange step
- Tried: full reinstall, cache clear, sign out/in — none resolved the issue

Steps to Reproduce

1. Install Claude Desktop v1.2.234 (build 1.569.0) on macOS 26.2 Tahoe (Build 25C56)
2. Open Claude Desktop
3. Click on the Cowork tab
4. Try to start a new session
5. Session fails immediately with "Unable to start session. Check your internet connection and try again."

Note: Cowork worked correctly before updating to v1.2.234 on April 2, 2026.
Also reproducible: Claude Desktop → Check for Updates → fails with TLS error.

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unknown exact version, but Cowork was working correctly before the update installed on April 2, 2026. Current broken version is v1.2.234 (build 1.569.0).

Claude Code Version

N/A — this is a Claude Desktop (desktop app) issue, not Claude Code CLI. Claude Desktop v1.2.234 (build 1.569.0) macOS 26.2 Tahoe (Build 25C56)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

• Regular chat in Claude Desktop works perfectly — only Cowork is affected
• Cowork VM starts successfully (API reachability: REACHABLE in cowork_vm_node.log)
• Failure is specifically in the OAuth exchange step, before the session reaches the VM
• curl to api.anthropic.com and console.anthropic.com works fine from terminal (TLS ok, Google Trust Services cert, no interception)
• No VPN, no proxy, no corporate firewall, no security software (only Logitech G HUB extensions)
• scutil --proxy shows no proxy configured
• Full reinstall (removed app + all ~/Library/Application Support/Claude data), cache clear, and sign out/in did not resolve the issue
• Error code -1200 / NSURLErrorDomain suggests Electron's internal TLS stack is failing, while macOS system TLS (curl) works fine
• This appears to be a regression introduced in v1.2.234 affecting macOS 26.2 Tahoe

Related issues:

• #37077 — ECONNRESET not retried (same symptom, different context)
• #24470 — Cowork SSL error on macOS personal network (similar pattern)