[BUG] Cowork download_and_sdk_prepare fails after auto-update — server-side SDK endpoint rejection, not network issue

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?

Title: Cowork download_and_sdk_prepare fails after auto-update to 1.1.7714 — server-side SDK endpoint rejection, not network issue
Environment:

Claude Desktop version: 1.1.8308 (2498e4)
OS: macOS Tahoe 26.3.1 (25D2128), Darwin 25.3.0
Hardware: MacBook Pro 14-inch Nov 2024, Apple M4 Max, 36GB RAM
Architecture: arm64

What's wrong:
Cowork was working normally until March 19, 2026 at ~1:24pm when Claude Desktop auto-updated to 1.1.7714. Every startup attempt since then fails at the download_and_sdk_prepare step with "Download failed. Check your internet connection and try again." — despite internet being fully functional.
Root cause identified from logs:
The download_and_sdk_prepare step fails in 3–12 seconds consistently — too fast to be a real download attempt. The VM bundle (rootfs.img) is present, decompresses successfully from local cache, and logs confirm "All files ready" — but the step still fails immediately after. This points to the SDK download endpoint returning an error or rejecting the request, not a local or network issue.
Last successful session: March 19, 4:19am, SDK version 2.1.74 installed successfully.
First failure: March 19, 1:24pm, immediately after auto-update. One entry shows net::ERR_NETWORK_CHANGED during the transition, suggesting the update interrupted an active session and corrupted the startup state.
Evidence this is server-side, not local:

Fails on 5+ different WiFi networks and mobile hotspot
Fails across two different Claude Desktop versions (1.1.7714 and 1.1.8308)
Full uninstall + reinstall does not fix it
Deleted vm_bundles directory, let it re-download — still fails
grep -i cowork on node_modules in the app bundle returns nothing (runtime missing from packaging)
yukonSilver shows as supported in supported-features-info.json
VM bundle exists, is downloaded, decompresses fine — failure is specifically at SDK prep

Relevant log entries (cowork_vm_node.log):
2026-03-19 13:26:30 [error] [download] VM download failed: Request error: net::ERR_NETWORK_CHANGED
2026-03-19 13:51:51 [error] [VM:steps] download_and_sdk_prepare failed (658931ms): Download failed.
2026-03-24 17:17:02 [info] All files ready in .../claudevm.bundle
2026-03-24 17:17:02 [error] [VM:steps] download_and_sdk_prepare failed (11688ms): Download failed.
Steps to reproduce:

Open Claude Desktop 1.1.8308 on macOS Tahoe 26.3.1
Navigate to Cowork tab
Observe immediate "Failed to start Claude's workspace / Download failed" error

What I've tried:

Restarted app and computer multiple times
Deleted vm_bundles and let it re-download
Full uninstall and reinstall twice (from claude.ai/download)
Tested on 5+ different networks including mobile hotspot
Disabled Norton antivirus
Checked node_modules for cowork runtime — returns nothing (missing from bundle)

Expected: Cowork starts and SDK installs as it did successfully on March 19 at 4:19am with SDK 2.1.74.
Actual: download_and_sdk_prepare fails every time in under 12 seconds after "All files ready" is confirmed.

What Should Happen?

Cowork workspace starts successfully, VM boots, and SDK installs as it did on March 19 at 4:19am with SDK version 2.1.74

Error Messages/Logs

Paste these into the Error Messages/Logs box:


2026-03-19 13:26:30 [error] [download] VM download failed: Request error: net::ERR_NETWORK_CHANGED
2026-03-19 13:51:51 [error] [VM:steps] download_and_sdk_prepare failed (658931ms): Download failed. Check your internet connection and try again.
2026-03-24 17:17:02 [info] All files ready in /Users/jacob/Library/Application Support/Claude/vm_bundles/claudevm.bundle
2026-03-24 17:17:02 [error] [VM:steps] download_and_sdk_prepare failed (11688ms): Download failed. Check your internet connection and try again.
2026-03-24 17:17:02 [error] [VM:start] Startup failed: Error: Download failed. Check your internet connection and try again.
2026-03-19 04:19:23 [info] [postConnect] Installing SDK: subpath=Library/Application Support/Claude/claude-code-vm, version=2.1.74
(^ last successful SDK install before update broke it)

Steps to Reproduce

1. Open Claude Desktop 1.1.8308 on macOS Tahoe 26.3.1
2. Navigate to Cowork tab
3. Observe "Failed to start Claude's workspace / Download failed" error immediately

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.1.7464 (last working was March 19, 4:19am before auto-update to 1.1.7714)

Claude Code Version

N/A - issue is with Claude Desktop Cowork, not Claude Code CLI

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Cowork runtime missing from app bundle — ls /Applications/Claude.app/Contents/Resources/app.asar.unpacked/node_modules/ | grep -i cowork returns nothing. Tested on 5+ WiFi networks and mobile hotspot. Norton disabled. Full uninstall/reinstall twice. vm_bundles deleted and re-downloaded. yukonSilver shows as supported in supported-features-info.json.

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