### Preflight Checklist - [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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? What's Wrong? Cowork consistently fails to start with "Failed to start Claude's workspace — Can't reach the Claude API from Claude's workspace." Regular C

[BUG] Win 11 Pro, 24H2, Build 26100.7840, Hyper-V enabled, ECONNRESET error

Resolved 💬 3 comments Opened Feb 15, 2026 by matdjolic-arch Closed Feb 18, 2026

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?

What's Wrong?
Cowork consistently fails to start with "Failed to start Claude's workspace — Can't reach the Claude API from Claude's workspace." Regular Chat mode works perfectly. Only Cowork is affected.
The error progresses through these stages:

"Failed to start Claude's workspace — Can't reach the Claude API from Claude's workspace"
API Error: Unable to connect to API (ECONNRESET)
After additional troubleshooting: sdk-daemon not connected Environment

Claude Desktop Version: Latest (downloaded Feb 2026)
Platform: Windows 11 Pro
Windows Version: 24H2
OS Build: 26100.7840
Hyper-V: Enabled (full, including sub-features)
Virtual Machine Platform: Enabled
Windows Hypervisor Platform: Enabled
Subscription: Paid plan

Steps to Reproduce

Install Claude Desktop on Windows 11 Pro (24H2, Build 26100.7840)
Log in with paid subscription
Switch to the Cowork tab
Workspace attempts to start
Fails with "Can't reach the Claude API from Claude's workspace

What Should Happen?

<html>
<body>
<p class="font-claude-response-body break-words whitespace-normal leading-[1.7]">Cowork workspace should start successfully and connect to the Claude API, the same way regular Chat mode works without issues.</p>
<h2 class="text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold">Troubleshooting Already Attempted (all failed)</h2>
<ol class="[li_&]:mb-0 [li_&]:mt-1 [li_&]:gap-1 [&:not(:last-child)_ul]:pb-1 [&:not(:last-child)_ol]:pb-1 list-decimal flex flex-col gap-1 pl-8 mb-3">
<li class="whitespace-normal break-words pl-2"><strong>Verified host API connectivity:</strong>
<ul class="[li_&]:mb-0 [li_&]:mt-1 [li_&]:gap-1 [&:not(:last-child)_ul]:pb-1 [&:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3">
<li class="whitespace-normal break-words pl-2"><code class="bg-text-200/5 border border-0.5 border-border-300 text-danger-000 whitespace-pre-wrap rounded-[0.4rem] px-1 py-px text-[0.9rem]">Test-NetConnection api.anthropic.com -Port 443</code> → TcpTestSucceeded: <strong>True</strong></li>
<li class="whitespace-normal break-words pl-2">Host machine can reach the API with no issues</li>
</ul>
</li>
<li class="whitespace-normal break-words pl-2"><strong>Enabled all virtualisation features:</strong>
<ul class="[li_&]:mb-0 [li_&]:mt-1 [li_&]:gap-1 [&:not(:last-child)_ul]:pb-1 [&:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3">
<li class="whitespace-normal break-words pl-2">Hyper-V (full, with all sub-features) ✅</li>
<li class="whitespace-normal break-words pl-2">Virtual Machine Platform ✅</li>
<li class="whitespace-normal break-words pl-2">Windows Hypervisor Platform ✅</li>
</ul>
</li>
<li class="whitespace-normal break-words pl-2"><strong>Disabled Windows Defender Firewall</strong> (Domain, Private, Public) — no change</li>
<li class="whitespace-normal break-words pl-2"><strong>Manually configured NAT networking:</strong>
<ul class="[li_&]:mb-0 [li_&]:mt-1 [li_&]:gap-1 [&:not(:last-child)_ul]:pb-1 [&:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3">
<li class="whitespace-normal break-words pl-2">Created internal VMSwitch (<code class="bg-text-200/5 border border-0.5 border-border-300 text-danger-000 whitespace-pre-wrap rounded-[0.4rem] px-1 py-px text-[0.9rem]">cowork-vm-nat</code>)</li>
<li class="whitespace-normal break-words pl-2">Assigned IP address (172.20.0.1/24)</li>
<li class="whitespace-normal break-words pl-2">Created NetNat rule</li>
<li class="whitespace-normal break-words pl-2">Error changed from ECONNRESET to <code class="bg-text-200/5 border border-0.5 border-border-300 text-danger-000 whitespace-pre-wrap rounded-[0.4rem] px-1 py-px text-[0.9rem]">sdk-daemon not connected</code>, suggesting the VM got network access but still couldn't reach the API</li>
</ul>
</li>
<li class="whitespace-normal break-words pl-2"><strong>Cleared cache and restarted</strong> via Help → Troubleshooting → Clear cache and restart</li>
<li class="whitespace-normal break-words pl-2"><strong>Deleted vm_bundles folder</strong> and let Claude re-download the VM fresh — no change</li>
<li class="whitespace-normal break-words pl-2"><strong>Removed manual NAT configuration</strong> to avoid conflicts — reverted to default state</li>
<li class="whitespace-normal break-words pl-2"><strong>No VPN or proxy</strong> running on the system</li>
</ol>
<h2 class="text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold">Network Adapters</h2>
<div class="overflow-x-auto w-full px-2 mb-6">
Adapter | Type | Status
-- | -- | --
Default Switch | Internal (Hyper-V) | Up
Wi-Fi | Physical | Up

</div>
<h2 class="text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold">Key Observations</h2>
<ul class="[li_&]:mb-0 [li_&]:mt-1 [li_&]:gap-1 [&:not(:last-child)_ul]:pb-1 [&:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3">
<li class="whitespace-normal break-words pl-2">Host machine reaches <code class="bg-text-200/5 border border-0.5 border-border-300 text-danger-000 whitespace-pre-wrap rounded-[0.4rem] px-1 py-px text-[0.9rem]">api.anthropic.com:443</code> successfully (TcpTestSucceeded: True, resolved to 160.79.104.10 via IPv4)</li>
<li class="whitespace-normal break-words pl-2">Regular Chat mode works perfectly — only Cowork is broken</li>
<li class="whitespace-normal break-words pl-2">The VM appears to boot and get network access, but cannot route traffic to the Claude API</li>
<li class="whitespace-normal break-words pl-2">This matches other reported issues (#24918, #24945, #25205) suggesting a systemic problem with the VM's outbound API connectivity on Windows</li></ul>
</body>
</html>

Error Messages/Logs

Steps to Reproduce

Install Claude Desktop on a Windows 11 Pro machine
Log in with your paid account
Click the Cowork tab
Try to start a task
See it fail with the API connection error

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Version 1.1.3189 (1b7b58)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_

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